Carol A. Burke, MD

Traditionally, a hereditary colorectal cancer syndrome (HCCS) was suspected in individuals with an obvious personal and/or family cancer phenotype informed by a three-generation family cancer history. Family history is still required to inform cancer risk. Documentation of age at cancer diagnosis, age of relatives’ deaths, and key intestinal and extraintestinal features of a HCCS (for example, macrocephaly, café au lait spots, polyp number, size, and histology) are requisite. Historically, Sanger sequencing was used to determine the presence of a suspected single pathogenic germline variant (PGV). If no PGV was detected, another PGV would be sought. This old “single gene/single syndrome” testing was expensive, time consuming, and inefficient, and has been supplanted by multigene cancer panel testing (MGPT). MGPT-driven low-cost, high-throughput testing has widespread insurance coverage in eligible patients. Since considerable clinical phenotypic overlap exists between HCCSs, casting a broader net for determining PGV, compared with a more limited approach, allows for greater identification of carriers of PGV as well as variants of uncertain significance.

The frequency of PGV detection by MGPT in individuals with CRC is dependent on age at diagnosis and presence of DNA mismatch repair (MMR) deficiency in the tumor. According to one review, PGVs on MGPT are detected in approximately 10% and 34% of individuals aged more than 50 and more than 35 years, respectively.¹ Pearlman and colleagues performed MGPT in 450 patients with CRC less than 50 years.² PGV were found in 8% and 83.3% of cases with MMR-proficient and -deficient tumors, respectively. Overall, 33.3% of patients did not meet genetic testing criteria for the gene in which a PGV was detected, raising the impetus to consider MGPT in all patients with CRC. The Collaborative Group of the Americas on Inherited Gastrointestinal Cancer and National Comprehensive Cancer Network provide guidance on who warrants PGV testing.^3,4

Germline testing outcomes and general approaches to patient management are provided in the graphic. HCCS are common and MGPT has broadened the identification of carriers of PGVs. In spite of advances in genetic testing technology, family history remains crucial to deploying risk-mitigation measures, regardless of the results of genetic testing.

Dr. Burke is in the department of gastroenterology, hepatology, and nutrition at the Cleveland Clinic. She disclosed ties to Janssen Pharma, Emtora Biosciences, Freenome, SLA Pharma, and Ambry Genetics. Dr. Burke is a member of the U.S. Multi-Society Task Force on Colorectal Cancer, National Comprehensive Cancer Network Guideline on Genetic/Familial High-Risk Assessment: Colorectal. These remarks were made during one of the AGA Postgraduate Course sessions held at DDW 2022.

References

1. Stoffel E and Murphy CC. Gastroenterology. 2020 Jan;158(2):341-353.

2. Pearlman R et al. JAMA Oncol. 2017 Apr 1;3(4):464-471.

3. Heald B et al. Fam Cancer. 2020 Jul;19(3):223-239.

4. National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology: Genetic/Familial High-Risk Assessment: Colorectal Version 1.2022. 2022 Jun 8. 

Traditionally, a hereditary colorectal cancer syndrome (HCCS) was suspected in individuals with an obvious personal and/or family cancer phenotype informed by a three-generation family cancer history. Family history is still required to inform cancer risk. Documentation of age at cancer diagnosis, age of relatives’ deaths, and key intestinal and extraintestinal features of a HCCS (for example, macrocephaly, café au lait spots, polyp number, size, and histology) are requisite. Historically, Sanger sequencing was used to determine the presence of a suspected single pathogenic germline variant (PGV). If no PGV was detected, another PGV would be sought. This old “single gene/single syndrome” testing was expensive, time consuming, and inefficient, and has been supplanted by multigene cancer panel testing (MGPT). MGPT-driven low-cost, high-throughput testing has widespread insurance coverage in eligible patients. Since considerable clinical phenotypic overlap exists between HCCSs, casting a broader net for determining PGV, compared with a more limited approach, allows for greater identification of carriers of PGV as well as variants of uncertain significance.

The frequency of PGV detection by MGPT in individuals with CRC is dependent on age at diagnosis and presence of DNA mismatch repair (MMR) deficiency in the tumor. According to one review, PGVs on MGPT are detected in approximately 10% and 34% of individuals aged more than 50 and more than 35 years, respectively.¹ Pearlman and colleagues performed MGPT in 450 patients with CRC less than 50 years.² PGV were found in 8% and 83.3% of cases with MMR-proficient and -deficient tumors, respectively. Overall, 33.3% of patients did not meet genetic testing criteria for the gene in which a PGV was detected, raising the impetus to consider MGPT in all patients with CRC. The Collaborative Group of the Americas on Inherited Gastrointestinal Cancer and National Comprehensive Cancer Network provide guidance on who warrants PGV testing.^3,4

Germline testing outcomes and general approaches to patient management are provided in the graphic. HCCS are common and MGPT has broadened the identification of carriers of PGVs. In spite of advances in genetic testing technology, family history remains crucial to deploying risk-mitigation measures, regardless of the results of genetic testing.

Dr. Burke is in the department of gastroenterology, hepatology, and nutrition at the Cleveland Clinic. She disclosed ties to Janssen Pharma, Emtora Biosciences, Freenome, SLA Pharma, and Ambry Genetics. Dr. Burke is a member of the U.S. Multi-Society Task Force on Colorectal Cancer, National Comprehensive Cancer Network Guideline on Genetic/Familial High-Risk Assessment: Colorectal. These remarks were made during one of the AGA Postgraduate Course sessions held at DDW 2022.

References

1. Stoffel E and Murphy CC. Gastroenterology. 2020 Jan;158(2):341-353.

2. Pearlman R et al. JAMA Oncol. 2017 Apr 1;3(4):464-471.

3. Heald B et al. Fam Cancer. 2020 Jul;19(3):223-239.

4. National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology: Genetic/Familial High-Risk Assessment: Colorectal Version 1.2022. 2022 Jun 8. 

Traditionally, a hereditary colorectal cancer syndrome (HCCS) was suspected in individuals with an obvious personal and/or family cancer phenotype informed by a three-generation family cancer history. Family history is still required to inform cancer risk. Documentation of age at cancer diagnosis, age of relatives’ deaths, and key intestinal and extraintestinal features of a HCCS (for example, macrocephaly, café au lait spots, polyp number, size, and histology) are requisite. Historically, Sanger sequencing was used to determine the presence of a suspected single pathogenic germline variant (PGV). If no PGV was detected, another PGV would be sought. This old “single gene/single syndrome” testing was expensive, time consuming, and inefficient, and has been supplanted by multigene cancer panel testing (MGPT). MGPT-driven low-cost, high-throughput testing has widespread insurance coverage in eligible patients. Since considerable clinical phenotypic overlap exists between HCCSs, casting a broader net for determining PGV, compared with a more limited approach, allows for greater identification of carriers of PGV as well as variants of uncertain significance.

The frequency of PGV detection by MGPT in individuals with CRC is dependent on age at diagnosis and presence of DNA mismatch repair (MMR) deficiency in the tumor. According to one review, PGVs on MGPT are detected in approximately 10% and 34% of individuals aged more than 50 and more than 35 years, respectively.¹ Pearlman and colleagues performed MGPT in 450 patients with CRC less than 50 years.² PGV were found in 8% and 83.3% of cases with MMR-proficient and -deficient tumors, respectively. Overall, 33.3% of patients did not meet genetic testing criteria for the gene in which a PGV was detected, raising the impetus to consider MGPT in all patients with CRC. The Collaborative Group of the Americas on Inherited Gastrointestinal Cancer and National Comprehensive Cancer Network provide guidance on who warrants PGV testing.^3,4

Germline testing outcomes and general approaches to patient management are provided in the graphic. HCCS are common and MGPT has broadened the identification of carriers of PGVs. In spite of advances in genetic testing technology, family history remains crucial to deploying risk-mitigation measures, regardless of the results of genetic testing.

Dr. Burke is in the department of gastroenterology, hepatology, and nutrition at the Cleveland Clinic. She disclosed ties to Janssen Pharma, Emtora Biosciences, Freenome, SLA Pharma, and Ambry Genetics. Dr. Burke is a member of the U.S. Multi-Society Task Force on Colorectal Cancer, National Comprehensive Cancer Network Guideline on Genetic/Familial High-Risk Assessment: Colorectal. These remarks were made during one of the AGA Postgraduate Course sessions held at DDW 2022.

References

1. Stoffel E and Murphy CC. Gastroenterology. 2020 Jan;158(2):341-353.

2. Pearlman R et al. JAMA Oncol. 2017 Apr 1;3(4):464-471.

3. Heald B et al. Fam Cancer. 2020 Jul;19(3):223-239.

4. National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology: Genetic/Familial High-Risk Assessment: Colorectal Version 1.2022. 2022 Jun 8. 

In Reply: We thank the readers for their interest in our paper.

Drs. Goldstein, Mascitelli, and Rauf point out the concerning epidemiologic increase in the incidence of colorectal cancer (CRC) among individuals under the age of 50 and suggest folate as a potential cause.¹

The underlying cause of the rise in incidence is unknown, and many environmental and lifestyle risk factors have been proposed.^2–4 Black men have historically had and continue to have the highest incidence of and stage-adjusted mortality from CRC, but the rise of CRC in the young is a phenomenon in whites.¹ Furthermore, these cancers are left-sided. Other known and proposed risk factors associated with this phenomenon include dietary and lifestyle factors such as alcohol consumption, smoking, obesity, and consumption of processed and red meat.^5–7

The cohort effect of rising colon and rectal cancer incidence in younger individuals is likely due to changes in the microbiome. Antibiotic exposure is widespread and has been conjectured as a cause, as has folate supplementation, which began in the United States in 1998. Folic acid has been shown to be associated with both protective and harmful effects on colorectal neoplasia.^8,9 While Goldstein et al recommend CRC screening starting at an early age in countries with folate supplementation, countries without folate supplementation have also noted a rise in early-onset CRC. For example, in Azerbaijan, the mean age at diagnosis of CRC in 546 individuals was 55.2 ± 11.5, and 23% had an age lower than 40 years. Nearly 60% presented at an advanced stage, and the majority of lesions were in the rectum.¹⁰

The impact of the confounding variables and risk factors resulting in the epidemiologic shift in young patients with CRC, along with the biology of the cancers, should be teased out. Once these are known, population screening guidelines can be adjusted. Until then, practitioners should personalize recommendations based on individual risk factors and promptly investigate colonic symptoms, no matter the age of the patient.

We also thank Drs. Joseph Weiss, Nancy Cetel, and Danielle Weiss for their thoughtful analysis of our article. Our intent was to highlight 2 of the most utilized options available for CRC screening and surveillance in the United States. As we pointed out, the choice of test depends on patient preference, family history, and the likelihood of compliance. The goal of any screening program is outreach and adherence, which is optimized when patients are offered a choice of tests.^11–13Table 1 from our article shows the options available.¹⁴

When discussing these options with patients, several factors should be taken into consideration. It is important that patients have an understanding of how tests are performed: stool-based vs imaging, bowel prep vs no prep, and frequency of testing.¹⁵ Any screening test short of colonoscopy that is positive leads to colonoscopy. Also, programmatic noncolonoscopic screening tests require a system of patient navigation for both positive and negative results. An individual may be more likely to complete 1 test such as screening colonoscopy every 10 years vs another test annually.

A common misconception about computed tomography colonography is that it is similar to computed tomography of the abdomen with a focus on the colon. Individuals may still have to undergo a bowel preparation and dietary restrictions before the procedure. Furthermore, a rectal catheter is used to insufflate and distend the colon prior to capturing images, which many patients find uncomfortable.¹⁶ Finally, the incidental discovery of extracolonic lesions may result in unnecessary testing.¹⁷

The sensitivity and specificity of each test and operator variability in accuracy and quality should also be highlighted. For example, the sensitivity of a one-time fecal immunochemical test to detect an advanced adenoma may be as low as 25%.¹⁸ All testing modalities are diagnostic, but only colonoscopy is therapeutic.

We agree that clinicians who perform CRC screening have an armamentarium of tests to offer, and the advantages and disadvantages of each should be carefully considered and individualized.

In Reply: We thank the readers for their interest in our paper.

Drs. Goldstein, Mascitelli, and Rauf point out the concerning epidemiologic increase in the incidence of colorectal cancer (CRC) among individuals under the age of 50 and suggest folate as a potential cause.¹

The underlying cause of the rise in incidence is unknown, and many environmental and lifestyle risk factors have been proposed.^2–4 Black men have historically had and continue to have the highest incidence of and stage-adjusted mortality from CRC, but the rise of CRC in the young is a phenomenon in whites.¹ Furthermore, these cancers are left-sided. Other known and proposed risk factors associated with this phenomenon include dietary and lifestyle factors such as alcohol consumption, smoking, obesity, and consumption of processed and red meat.^5–7

The cohort effect of rising colon and rectal cancer incidence in younger individuals is likely due to changes in the microbiome. Antibiotic exposure is widespread and has been conjectured as a cause, as has folate supplementation, which began in the United States in 1998. Folic acid has been shown to be associated with both protective and harmful effects on colorectal neoplasia.^8,9 While Goldstein et al recommend CRC screening starting at an early age in countries with folate supplementation, countries without folate supplementation have also noted a rise in early-onset CRC. For example, in Azerbaijan, the mean age at diagnosis of CRC in 546 individuals was 55.2 ± 11.5, and 23% had an age lower than 40 years. Nearly 60% presented at an advanced stage, and the majority of lesions were in the rectum.¹⁰

The impact of the confounding variables and risk factors resulting in the epidemiologic shift in young patients with CRC, along with the biology of the cancers, should be teased out. Once these are known, population screening guidelines can be adjusted. Until then, practitioners should personalize recommendations based on individual risk factors and promptly investigate colonic symptoms, no matter the age of the patient.

We also thank Drs. Joseph Weiss, Nancy Cetel, and Danielle Weiss for their thoughtful analysis of our article. Our intent was to highlight 2 of the most utilized options available for CRC screening and surveillance in the United States. As we pointed out, the choice of test depends on patient preference, family history, and the likelihood of compliance. The goal of any screening program is outreach and adherence, which is optimized when patients are offered a choice of tests.^11–13Table 1 from our article shows the options available.¹⁴

When discussing these options with patients, several factors should be taken into consideration. It is important that patients have an understanding of how tests are performed: stool-based vs imaging, bowel prep vs no prep, and frequency of testing.¹⁵ Any screening test short of colonoscopy that is positive leads to colonoscopy. Also, programmatic noncolonoscopic screening tests require a system of patient navigation for both positive and negative results. An individual may be more likely to complete 1 test such as screening colonoscopy every 10 years vs another test annually.

A common misconception about computed tomography colonography is that it is similar to computed tomography of the abdomen with a focus on the colon. Individuals may still have to undergo a bowel preparation and dietary restrictions before the procedure. Furthermore, a rectal catheter is used to insufflate and distend the colon prior to capturing images, which many patients find uncomfortable.¹⁶ Finally, the incidental discovery of extracolonic lesions may result in unnecessary testing.¹⁷

The sensitivity and specificity of each test and operator variability in accuracy and quality should also be highlighted. For example, the sensitivity of a one-time fecal immunochemical test to detect an advanced adenoma may be as low as 25%.¹⁸ All testing modalities are diagnostic, but only colonoscopy is therapeutic.

We agree that clinicians who perform CRC screening have an armamentarium of tests to offer, and the advantages and disadvantages of each should be carefully considered and individualized.

In Reply: We thank the readers for their interest in our paper.

Drs. Goldstein, Mascitelli, and Rauf point out the concerning epidemiologic increase in the incidence of colorectal cancer (CRC) among individuals under the age of 50 and suggest folate as a potential cause.¹

The underlying cause of the rise in incidence is unknown, and many environmental and lifestyle risk factors have been proposed.^2–4 Black men have historically had and continue to have the highest incidence of and stage-adjusted mortality from CRC, but the rise of CRC in the young is a phenomenon in whites.¹ Furthermore, these cancers are left-sided. Other known and proposed risk factors associated with this phenomenon include dietary and lifestyle factors such as alcohol consumption, smoking, obesity, and consumption of processed and red meat.^5–7

The cohort effect of rising colon and rectal cancer incidence in younger individuals is likely due to changes in the microbiome. Antibiotic exposure is widespread and has been conjectured as a cause, as has folate supplementation, which began in the United States in 1998. Folic acid has been shown to be associated with both protective and harmful effects on colorectal neoplasia.^8,9 While Goldstein et al recommend CRC screening starting at an early age in countries with folate supplementation, countries without folate supplementation have also noted a rise in early-onset CRC. For example, in Azerbaijan, the mean age at diagnosis of CRC in 546 individuals was 55.2 ± 11.5, and 23% had an age lower than 40 years. Nearly 60% presented at an advanced stage, and the majority of lesions were in the rectum.¹⁰

The impact of the confounding variables and risk factors resulting in the epidemiologic shift in young patients with CRC, along with the biology of the cancers, should be teased out. Once these are known, population screening guidelines can be adjusted. Until then, practitioners should personalize recommendations based on individual risk factors and promptly investigate colonic symptoms, no matter the age of the patient.

We also thank Drs. Joseph Weiss, Nancy Cetel, and Danielle Weiss for their thoughtful analysis of our article. Our intent was to highlight 2 of the most utilized options available for CRC screening and surveillance in the United States. As we pointed out, the choice of test depends on patient preference, family history, and the likelihood of compliance. The goal of any screening program is outreach and adherence, which is optimized when patients are offered a choice of tests.^11–13Table 1 from our article shows the options available.¹⁴

When discussing these options with patients, several factors should be taken into consideration. It is important that patients have an understanding of how tests are performed: stool-based vs imaging, bowel prep vs no prep, and frequency of testing.¹⁵ Any screening test short of colonoscopy that is positive leads to colonoscopy. Also, programmatic noncolonoscopic screening tests require a system of patient navigation for both positive and negative results. An individual may be more likely to complete 1 test such as screening colonoscopy every 10 years vs another test annually.

A common misconception about computed tomography colonography is that it is similar to computed tomography of the abdomen with a focus on the colon. Individuals may still have to undergo a bowel preparation and dietary restrictions before the procedure. Furthermore, a rectal catheter is used to insufflate and distend the colon prior to capturing images, which many patients find uncomfortable.¹⁶ Finally, the incidental discovery of extracolonic lesions may result in unnecessary testing.¹⁷

The sensitivity and specificity of each test and operator variability in accuracy and quality should also be highlighted. For example, the sensitivity of a one-time fecal immunochemical test to detect an advanced adenoma may be as low as 25%.¹⁸ All testing modalities are diagnostic, but only colonoscopy is therapeutic.

We agree that clinicians who perform CRC screening have an armamentarium of tests to offer, and the advantages and disadvantages of each should be carefully considered and individualized.

Screening can help prevent colorectal cancer. The United States has seen a steady decline in colorectal cancer incidence and mortality, thanks in large part to screening. Screening rates can be increased with good patient-physician dialogue and by choosing a method the patient prefers and is most likely to complete.

In this article, we review a general approach to screening, focusing on the most commonly used methods in the United States, ie, the guaiac-based fecal occult blood test (FOBT), the fecal immunochemical test (FIT), and colonoscopy. We discuss current colorectal cancer incidence rates, screening recommendations, and how to choose the appropriate screening test.

This article does not discuss patients at high risk of polyps or cancer due to hereditary colon cancer syndromes, a personal history of colorectal neoplasia, inflammatory bowel disease, or primary sclerosing cholangitis.

TRENDS IN INCIDENCE

Colorectal cancer is the second most common type of cancer and cause of cancer-related deaths in the United States, responsible for an estimated 50,000 deaths in 2017. The lifetime risk of its occurrence is estimated to be 1 in 21 men and 1 in 23 women.¹ Encouragingly, the incidence has declined by 24% over the last 30 years,² and by 3% per year from 2004 to 2013.¹ Also, as a result of screening and advances in treatment, 5-year survival rates for patients with colorectal cancer have increased, from 48.6% in 1975 to 66.4% in 2009.²

When detected at a localized stage, the 5-year survival rate in colorectal cancer is greater than 90%. Unfortunately, it is diagnosed early in only 39% of patients. And despite advances in treatment and a doubling of the 5-year survival rate in patients with advanced cancers since 1990,³ the latter is only 14%. In most patients, cancer is diagnosed when it has spread to the lymph nodes (36%) or to distant organs (22%), and the survival rate declines to 71% after lymph-node spread, and 14% after metastasis to distant organs.

It is essential to screen people who have no symptoms, as symptoms such as gastrointestinal bleeding, unexplained abdominal pain or weight loss, a persistent change in bowel movements, and bowel obstruction typically do not arise until the disease is advanced and less amenable to cure.

Increasing prevalence in younger adults

Curiously, the incidence of colorectal cancer is increasing in white US adults under age 50. Over the last 30 years, incidence rates have increased from 1.0% to 2.4% annually in adults ages 20 to 39.⁴ Based on current trends, colon cancer rates are expected to increase by 90% for patients ages 20 to 34 and by 28% for patients 35 to 49 by 2030.⁵

Although recommendations vary for colorectal cancer screening in patients under age 50, clinicians should investigate symptoms such as rectal bleeding, unexplained iron deficiency anemia, progressive abdominal pain, and persistent changes in bowel movements.

Other challenges

Despite the benefits of screening, it is underutilized. Although rates of compliance with screening recommendations have increased 10% over the last 10 years, only 65% of eligible adults currently comply.^1,6

Additionally, certain areas of the country such as Appalachia and the Mississippi Delta have not benefited from the decline in the national rate of colorectal cancer.⁷

SCREENING GUIDELINES

Most guidelines say that colorectal cancer screening should begin at age 50 in people at average risk with no symptoms. However, the American College of Gastroenterology (ACG) recommends beginning screening at age 45 in African Americans, as this group has higher incidence and mortality rates of colorectal cancer.⁸ Also, the American Cancer Society recently recommended beginning screening at age 45 for all individuals.⁹

Screening can stop at age 75 for most patients, according to the ACG,⁸ the US Multi-Society Task Force on Colorectal Cancer,¹⁰ and the US Preventive Services Task Force  (USPSTF).¹¹ However, the decision should be individualized for patients ages 76 to 85. Patients within that age group who are in good health and have not previously been screened are more likely to benefit than those who have previously been screened and had a negative screening test. Patients over age 85 should not begin or continue screening, because of diminished benefit of screening in this age group, shorter life expectancy, advanced comorbid conditions, and the risks of colonoscopy and cancer treatment.

Patients and clinicians are encouraged to collaborate in deciding which screening method is appropriate. Patients adhere better when they are given a choice in the matter.^12–14 And adherence is the key to effective colorectal cancer screening.

Familiarity with the key characteristics of currently available colorectal cancer screening tests will facilitate discussion with patients.

Opportunistic vs programmatic screening

Screening can be classified according to the approach to the patient or population and the intent of the test. Most screening in the United States is opportunistic rather than programmatic—that is, the physician offers the patient screening at the point of service without systematic follow-up or patient re-engagement.

In a programmatic approach, the patient is offered screening through an organized program that streamlines services, reduces overscreening, and provides systematic follow-up of testing.

Stool studies such as FOBT and FIT do not reliably detect cancer precursors such as adenomas and serrated neoplasms. If an FOBT is positive, follow-up diagnostic colonoscopy is required. Unlike screening colonoscopy, diagnostic colonoscopy requires a copayment for Medicare patients, and this should be explained to the patient.

FIT and FOBT detect hemolyzed blood within a stool sample, FOBT by a chemical reaction, and FIT by detecting a globin-specific antibody. Colorectal cancer and some large adenomatous polyps may intermittently bleed and result in occult blood in the stool, iron deficiency anemia, or hematochezia.¹⁵

Fecal occult blood testing

Historically, FOBT was the stool test of choice for screening. It uses an indirect enzymatic reaction to detect hemolyzed blood in the stool. When a specimen containing hemoglobin is added to guaiac paper and a drop of hydrogen peroxide is added to “develop” it, the peroxidase activity of hemoglobin turns the guaiac blue.

Screening with FOBT involves annual testing of 3 consecutively passed stools from different days; FOBT should not be performed at the time of digital rectal examination or if the patient is having overt rectal, urinary, or menstrual bleeding.

Dietary and medication restrictions before and during the testing period are critical, as red meat contains hemoglobin, and certain vegetables (eg, radishes, turnips, cauliflower, cucumbers) contain peroxidase, all of which can cause a false-positive result. Waiting 3 days after the stool sample is collected to develop it can mitigate the peroxidase activity of vegetables.¹⁶ Vitamin C inhibits heme peroxidase activity and leads to false-negative results. Aspirin and high-dose nonsteroidal anti-inflammatory drugs can promote bleeding throughout the intestinal tract.¹⁷

In randomized controlled trials,^18–21 screening with FOBT reduced colorectal cancer mortality rates by 15% to 33%. The 30-year follow-up of a large US trial²² found a 32% relative reduction in mortality rates in patients randomized to annual screening, and a 22% relative reduction in those randomized to screening every 2 years. Despite the many possibilities for false-positive results, the specificity for detecting cancer has ranged from 86.7% to 97.3%, and the sensitivity from 37.1% to 79.4%, highlighting the benefit of colorectal cancer screening programs in unscreened populations.^23–26

FIT vs FOBT in current practice

FIT should replace FOBT as the preferred stool screening method. Instead of an enzymatic reaction that can be altered by food or medication, FIT utilizes an antibody specific to human globin to directly detect hemolyzed blood, thus eliminating the need to modify the diet or medications.²⁷ Additionally, only 1 stool specimen is needed, which may explain why the adherence rate was about 20% higher with FIT than with FOBT in most studies.^28–30

FIT has a sensitivity of 69% to 86% for colorectal cancer and a specificity of 92% to 95%.³¹ The sensitivity can be improved by lowering the threshold value for a positive test, but this is associated with a decrease in specificity. A single FIT has the same sensitivity and specificity as several samples.³²

In a large retrospective US cohort study of programmatic screening with FIT, Jensen et al³³ reported that 48% of 670,841 people who were offered testing actually did the test. Of the 48% who participated in the first round and remained eligible, 75% to 86% participated in subsequent rounds over 4 years. Those who had a positive result on FIT were supposed to undergo colonoscopy, but 22% did not.

The US Multi-Society Task Force on Colorectal Cancer³⁴ suggests that FIT-based screening programs aim for a target FIT completion rate of more than 60% and a target colonoscopy completion rate of more than 80% of patients with positive FITs. These benchmarks were derived from adherence rates in international FIT screening studies in average-risk populations.^35–39 (Note that the large US cohort described above³³ did not meet these goals.) Ideally, every patient with a positive FIT should undergo diagnostic colonoscopy, but in reality only 50% to 83% actually do. Methods shown to improve adherence include structured screening programs with routine performance reports, provider feedback, and involvement of patient navigators.^40–42

Accordingly, several aspects of stool-based testing need to be stressed with patients. Understanding that FOBT is recommended yearly is integral for optimal impact on colorectal cancer incidence and mortality rates.

Additionally, patients should be advised to undergo colonoscopy soon after a positive FIT, because delaying colonoscopy could give precancerous lesions time to progress in stage. The acceptable time between a positive FIT and colonoscopy has yet to be determined. However, a retrospective cohort study of 1.26 million screened patients with 107,000 positive FIT results demonstrated that the rates of cancer discovered on colonoscopy were similar when performed within 30 days or up to 10 months after a positive test. Detection rates increased from 3% to 4.8% at 10 months and to 7.9% at 12 months.⁴³

In modeling studies, Meester et al⁴⁴ showed the estimated lifetime risk and mortality rates from colorectal cancer and life-years gained from screening are significantly better when colonoscopy is completed within 2 weeks rather than 1 year after a positive FIT. Each additional month after 2 weeks incrementally affected these outcomes, with a 1.4% increase in cancer mortality. These data suggest that colonoscopy should be done soon after a positive FIT result and at a maximum of 10 months.^43,44

Screening with FOBT is a multistep process for patients that includes receiving the test kit, collecting the sample, preparing it, returning it, undergoing colonoscopy after a positive test, and repeating in 1 year if negative. The screening program should identify patients at average risk in whom screening is appropriate, ensure delivery of the test, verify the quality of collected samples for laboratory testing against the manufacturer’s recommendations, and report results. Report of a positive FOBT result should provide recommendations for follow-up.

Though evidence clearly supports screening annually or biennially (every 2 years) with FOBT, the ideal interval for FIT is undetermined. Modeling studies utilized by the USPSTF and Multi-Society Task Force demonstrate that colonoscopy and annual FIT result in similar life-years gained, while 2 population-based screening programs have demonstrated that a 2- or 3-year interval may be equally efficacious by lowering the threshold for a positive test.^38,45

Randomized controlled trials of screening colonoscopy vs annual and biennial FIT are currently under way. Cost-effectiveness analysis has shown that offering single-sample FITs at more frequent (annual) intervals performs better than multisample testing at less frequent intervals.^45–47

Compared with stool-based screening, colonoscopy has advantages, including a 10-year screening interval if bowel preparation is adequate and the examination shows no neoplasia, the ability to inspect the entire colon, and the ability to diagnose and treat lesions in the same session.

Screening colonoscopy visualizes the entire colon in more than 98% of cases, although it requires adequate bowel preparation for maximal polyp detection. It can be done safely with or without sedation.⁴⁸

While there are no available randomized controlled trial data on the impact of screening colonoscopy on cancer incidence or mortality, extensive case-control and cohort studies consistently show that screening colonoscopy reduces cancer incidence and mortality rates.^49–54 A US Veterans Administration study of more than 32,000 patients reported a 50% reduction in overall colorectal cancer mortality.⁵⁵ In a microsimulation modeling study that assumed 100% adherence, colonoscopy every 10 years and annual FIT in individuals ages 50 to 75 provided similar life-years gained per 1,000 people screened (270 for colonoscopy, 244 for FIT).⁵⁶

Well-established metrics for maximizing the effectiveness and quality of colonoscopy have been established (Table 2). The most important include the mucosa inspection time (withdrawal time) and adenoma detection rate.⁵⁷ Withdrawal time is directly correlated with adenoma detection, and a 6-minute minimum withdrawal time is recommended in screening colonoscopy examinations of patients at average risk when no polyps are found.⁵⁸ The adenoma detection rate is the strongest evidence-based metric, as each 1% increase in the adenoma detection rate over 19% is associated with a 3% decrease in the risk of colorectal cancer and a 5% decrease in death rate.⁵⁹ The average-risk screening adenoma detection rate differs based on sex: the rate is greater than 20% for women and greater than 30% for men.

Complications from screening, diagnostic, or therapeutic colonoscopy are infrequent but include perforation (4/10,000) and significant intestinal bleeding (8/10,000).^56–62

Patients with a first-degree relative under age 60 with advanced adenomas or colorectal cancer are considered at high risk and should begin screening colonoscopy at age 40, with repeat colonoscopy at 5-year intervals, given a trend toward advanced neoplasia detection compared with FIT.⁶³

Guidelines recently published by the Canadian Association of Gastroenterology and endorsed by the American Gastroenterological Association also support starting screening in high-risk individuals at age 40, with a surveillance interval of 5 to 10 years based on the number of first-degree relatives with colorectal cancer or adenomas.⁶⁴ Consensus statements were based on retrospective cohort, prospective case-controlled, and cross-sectional studies comparing the risk of colorectal cancer in individuals with a family history against those without a family history.

Randomized clinical trials comparing colonoscopy and FIT are under way. Interim analysis of a European trial in which asymptomatic adults ages 50 to 69 were randomized to 1-time colonoscopy (26,703 patients) vs FIT every 2 years (26,599 patients) found significantly higher participation rates in the FIT arm (34.2% vs 24.6%) but higher rates of nonadvanced adenomas (4.2% vs 0.4%) and advanced neoplasia (1.9% vs 0.9%) in the colonoscopy arm.⁶⁵ Cancer was detected in 0.1% in each arm. These findings correlate with those of another study showing higher participation with FIT but higher advanced neoplasia detection rates with colonoscopy.⁶⁶

Detection of precursor lesions is vital, as removing neoplasms is the main strategy to reduce colorectal cancer incidence. Accordingly, the advantage of colonoscopy was illustrated by a study that determined that 53 patients would need to undergo screening colonoscopy to detect 1 advanced adenoma or cancerous lesion, compared with 264 for FIT.⁶⁷

STARTING SCREEING AT AGE 45

The American Cancer Society recently provided a qualified recommendation to start colorectal cancer screening in all individuals at age 45 rather than 50.⁹ This recommendation was based on modeling studies demonstrating that starting screening at age 45 with colonoscopy every 10 years resulted in 25 life-years gained at the cost of 610 colonoscopies per 1,000 individuals. Alternative strategies included FIT, which resulted in an additional 26 life-years gained per 1,000 individuals screened, flexible sigmoidoscopy (23 life-years gained), and computed tomographic colonoscopy (22 life-years gained).

Rates of colorectal cancer are rising in adults under age 50, and 10,000 new cases are anticipated this year.^2,3 Currently, 22 million US adults are between the ages of 45 and 50. The system and support needed to perform screening in all adults over age 45 and a lack of direct evidence to support its benefits in the young population need to be considered before widespread acceptance of the American Cancer Society recommendations. However, if screening is considered, FIT with or without sigmoidoscopy may be appropriate, given that most cancers diagnosed in individuals under age 50 are left-sided.^4,5

Screening has not been proven to reduce all-cause mortality. Randomized controlled trials of FOBT and observational studies of colonoscopy show that screening reduces cancer incidence and mortality. Until the currently ongoing randomized controlled trials comparing colonoscopy with FIT are completed, their comparative impact on colorectal cancer end points is unknown.

PATIENT ADHERENCE IS KEY

FIT and colonoscopy are the most prevalent screening methods in the United States. Careful attention should be given to offer the screening option the patient is most likely to complete, as adherence is key to the benefit from colorectal cancer screening.

The National Colorectal Cancer Roundtable (nccrt.org), established in 1997 by the American Cancer Society and the US Centers for Disease Control and Prevention, is a national coalition of public and private organizations dedicated to reducing colorectal cancer incidence and mortality. The Roundtable waged a national campaign to achieve a colorectal cancer screening rate of 80% in eligible adults by 2018, a goal that was not met. Still, the potential for a substantial impact is a compelling reason to endorse adherence to colorectal cancer screening. The Roundtable provides many resources for physicians to enhance screening in their practice.

The United States has seen a steady decline in colorectal cancer incidence and mortality, mainly as a result of screening. Colorectal cancer is preventable with ensuring patients’ adherence to screening. Screening rates have been shown to increase with patient-provider dialogue and with selection of a screening program the patient prefers and is most likely to complete.

Screening can help prevent colorectal cancer. The United States has seen a steady decline in colorectal cancer incidence and mortality, thanks in large part to screening. Screening rates can be increased with good patient-physician dialogue and by choosing a method the patient prefers and is most likely to complete.

In this article, we review a general approach to screening, focusing on the most commonly used methods in the United States, ie, the guaiac-based fecal occult blood test (FOBT), the fecal immunochemical test (FIT), and colonoscopy. We discuss current colorectal cancer incidence rates, screening recommendations, and how to choose the appropriate screening test.

This article does not discuss patients at high risk of polyps or cancer due to hereditary colon cancer syndromes, a personal history of colorectal neoplasia, inflammatory bowel disease, or primary sclerosing cholangitis.

TRENDS IN INCIDENCE

Colorectal cancer is the second most common type of cancer and cause of cancer-related deaths in the United States, responsible for an estimated 50,000 deaths in 2017. The lifetime risk of its occurrence is estimated to be 1 in 21 men and 1 in 23 women.¹ Encouragingly, the incidence has declined by 24% over the last 30 years,² and by 3% per year from 2004 to 2013.¹ Also, as a result of screening and advances in treatment, 5-year survival rates for patients with colorectal cancer have increased, from 48.6% in 1975 to 66.4% in 2009.²

When detected at a localized stage, the 5-year survival rate in colorectal cancer is greater than 90%. Unfortunately, it is diagnosed early in only 39% of patients. And despite advances in treatment and a doubling of the 5-year survival rate in patients with advanced cancers since 1990,³ the latter is only 14%. In most patients, cancer is diagnosed when it has spread to the lymph nodes (36%) or to distant organs (22%), and the survival rate declines to 71% after lymph-node spread, and 14% after metastasis to distant organs.

It is essential to screen people who have no symptoms, as symptoms such as gastrointestinal bleeding, unexplained abdominal pain or weight loss, a persistent change in bowel movements, and bowel obstruction typically do not arise until the disease is advanced and less amenable to cure.

Increasing prevalence in younger adults

Curiously, the incidence of colorectal cancer is increasing in white US adults under age 50. Over the last 30 years, incidence rates have increased from 1.0% to 2.4% annually in adults ages 20 to 39.⁴ Based on current trends, colon cancer rates are expected to increase by 90% for patients ages 20 to 34 and by 28% for patients 35 to 49 by 2030.⁵

Although recommendations vary for colorectal cancer screening in patients under age 50, clinicians should investigate symptoms such as rectal bleeding, unexplained iron deficiency anemia, progressive abdominal pain, and persistent changes in bowel movements.

Other challenges

Despite the benefits of screening, it is underutilized. Although rates of compliance with screening recommendations have increased 10% over the last 10 years, only 65% of eligible adults currently comply.^1,6

Additionally, certain areas of the country such as Appalachia and the Mississippi Delta have not benefited from the decline in the national rate of colorectal cancer.⁷

SCREENING GUIDELINES

Most guidelines say that colorectal cancer screening should begin at age 50 in people at average risk with no symptoms. However, the American College of Gastroenterology (ACG) recommends beginning screening at age 45 in African Americans, as this group has higher incidence and mortality rates of colorectal cancer.⁸ Also, the American Cancer Society recently recommended beginning screening at age 45 for all individuals.⁹

Screening can stop at age 75 for most patients, according to the ACG,⁸ the US Multi-Society Task Force on Colorectal Cancer,¹⁰ and the US Preventive Services Task Force  (USPSTF).¹¹ However, the decision should be individualized for patients ages 76 to 85. Patients within that age group who are in good health and have not previously been screened are more likely to benefit than those who have previously been screened and had a negative screening test. Patients over age 85 should not begin or continue screening, because of diminished benefit of screening in this age group, shorter life expectancy, advanced comorbid conditions, and the risks of colonoscopy and cancer treatment.

Patients and clinicians are encouraged to collaborate in deciding which screening method is appropriate. Patients adhere better when they are given a choice in the matter.^12–14 And adherence is the key to effective colorectal cancer screening.

Familiarity with the key characteristics of currently available colorectal cancer screening tests will facilitate discussion with patients.

Opportunistic vs programmatic screening

Screening can be classified according to the approach to the patient or population and the intent of the test. Most screening in the United States is opportunistic rather than programmatic—that is, the physician offers the patient screening at the point of service without systematic follow-up or patient re-engagement.

In a programmatic approach, the patient is offered screening through an organized program that streamlines services, reduces overscreening, and provides systematic follow-up of testing.

Stool studies such as FOBT and FIT do not reliably detect cancer precursors such as adenomas and serrated neoplasms. If an FOBT is positive, follow-up diagnostic colonoscopy is required. Unlike screening colonoscopy, diagnostic colonoscopy requires a copayment for Medicare patients, and this should be explained to the patient.

FIT and FOBT detect hemolyzed blood within a stool sample, FOBT by a chemical reaction, and FIT by detecting a globin-specific antibody. Colorectal cancer and some large adenomatous polyps may intermittently bleed and result in occult blood in the stool, iron deficiency anemia, or hematochezia.¹⁵

Fecal occult blood testing

Historically, FOBT was the stool test of choice for screening. It uses an indirect enzymatic reaction to detect hemolyzed blood in the stool. When a specimen containing hemoglobin is added to guaiac paper and a drop of hydrogen peroxide is added to “develop” it, the peroxidase activity of hemoglobin turns the guaiac blue.

Screening with FOBT involves annual testing of 3 consecutively passed stools from different days; FOBT should not be performed at the time of digital rectal examination or if the patient is having overt rectal, urinary, or menstrual bleeding.

Dietary and medication restrictions before and during the testing period are critical, as red meat contains hemoglobin, and certain vegetables (eg, radishes, turnips, cauliflower, cucumbers) contain peroxidase, all of which can cause a false-positive result. Waiting 3 days after the stool sample is collected to develop it can mitigate the peroxidase activity of vegetables.¹⁶ Vitamin C inhibits heme peroxidase activity and leads to false-negative results. Aspirin and high-dose nonsteroidal anti-inflammatory drugs can promote bleeding throughout the intestinal tract.¹⁷

In randomized controlled trials,^18–21 screening with FOBT reduced colorectal cancer mortality rates by 15% to 33%. The 30-year follow-up of a large US trial²² found a 32% relative reduction in mortality rates in patients randomized to annual screening, and a 22% relative reduction in those randomized to screening every 2 years. Despite the many possibilities for false-positive results, the specificity for detecting cancer has ranged from 86.7% to 97.3%, and the sensitivity from 37.1% to 79.4%, highlighting the benefit of colorectal cancer screening programs in unscreened populations.^23–26

FIT vs FOBT in current practice

FIT should replace FOBT as the preferred stool screening method. Instead of an enzymatic reaction that can be altered by food or medication, FIT utilizes an antibody specific to human globin to directly detect hemolyzed blood, thus eliminating the need to modify the diet or medications.²⁷ Additionally, only 1 stool specimen is needed, which may explain why the adherence rate was about 20% higher with FIT than with FOBT in most studies.^28–30

FIT has a sensitivity of 69% to 86% for colorectal cancer and a specificity of 92% to 95%.³¹ The sensitivity can be improved by lowering the threshold value for a positive test, but this is associated with a decrease in specificity. A single FIT has the same sensitivity and specificity as several samples.³²

In a large retrospective US cohort study of programmatic screening with FIT, Jensen et al³³ reported that 48% of 670,841 people who were offered testing actually did the test. Of the 48% who participated in the first round and remained eligible, 75% to 86% participated in subsequent rounds over 4 years. Those who had a positive result on FIT were supposed to undergo colonoscopy, but 22% did not.

The US Multi-Society Task Force on Colorectal Cancer³⁴ suggests that FIT-based screening programs aim for a target FIT completion rate of more than 60% and a target colonoscopy completion rate of more than 80% of patients with positive FITs. These benchmarks were derived from adherence rates in international FIT screening studies in average-risk populations.^35–39 (Note that the large US cohort described above³³ did not meet these goals.) Ideally, every patient with a positive FIT should undergo diagnostic colonoscopy, but in reality only 50% to 83% actually do. Methods shown to improve adherence include structured screening programs with routine performance reports, provider feedback, and involvement of patient navigators.^40–42

Accordingly, several aspects of stool-based testing need to be stressed with patients. Understanding that FOBT is recommended yearly is integral for optimal impact on colorectal cancer incidence and mortality rates.

Additionally, patients should be advised to undergo colonoscopy soon after a positive FIT, because delaying colonoscopy could give precancerous lesions time to progress in stage. The acceptable time between a positive FIT and colonoscopy has yet to be determined. However, a retrospective cohort study of 1.26 million screened patients with 107,000 positive FIT results demonstrated that the rates of cancer discovered on colonoscopy were similar when performed within 30 days or up to 10 months after a positive test. Detection rates increased from 3% to 4.8% at 10 months and to 7.9% at 12 months.⁴³

In modeling studies, Meester et al⁴⁴ showed the estimated lifetime risk and mortality rates from colorectal cancer and life-years gained from screening are significantly better when colonoscopy is completed within 2 weeks rather than 1 year after a positive FIT. Each additional month after 2 weeks incrementally affected these outcomes, with a 1.4% increase in cancer mortality. These data suggest that colonoscopy should be done soon after a positive FIT result and at a maximum of 10 months.^43,44

Screening with FOBT is a multistep process for patients that includes receiving the test kit, collecting the sample, preparing it, returning it, undergoing colonoscopy after a positive test, and repeating in 1 year if negative. The screening program should identify patients at average risk in whom screening is appropriate, ensure delivery of the test, verify the quality of collected samples for laboratory testing against the manufacturer’s recommendations, and report results. Report of a positive FOBT result should provide recommendations for follow-up.

Though evidence clearly supports screening annually or biennially (every 2 years) with FOBT, the ideal interval for FIT is undetermined. Modeling studies utilized by the USPSTF and Multi-Society Task Force demonstrate that colonoscopy and annual FIT result in similar life-years gained, while 2 population-based screening programs have demonstrated that a 2- or 3-year interval may be equally efficacious by lowering the threshold for a positive test.^38,45

Randomized controlled trials of screening colonoscopy vs annual and biennial FIT are currently under way. Cost-effectiveness analysis has shown that offering single-sample FITs at more frequent (annual) intervals performs better than multisample testing at less frequent intervals.^45–47

Compared with stool-based screening, colonoscopy has advantages, including a 10-year screening interval if bowel preparation is adequate and the examination shows no neoplasia, the ability to inspect the entire colon, and the ability to diagnose and treat lesions in the same session.

Screening colonoscopy visualizes the entire colon in more than 98% of cases, although it requires adequate bowel preparation for maximal polyp detection. It can be done safely with or without sedation.⁴⁸

While there are no available randomized controlled trial data on the impact of screening colonoscopy on cancer incidence or mortality, extensive case-control and cohort studies consistently show that screening colonoscopy reduces cancer incidence and mortality rates.^49–54 A US Veterans Administration study of more than 32,000 patients reported a 50% reduction in overall colorectal cancer mortality.⁵⁵ In a microsimulation modeling study that assumed 100% adherence, colonoscopy every 10 years and annual FIT in individuals ages 50 to 75 provided similar life-years gained per 1,000 people screened (270 for colonoscopy, 244 for FIT).⁵⁶

Well-established metrics for maximizing the effectiveness and quality of colonoscopy have been established (Table 2). The most important include the mucosa inspection time (withdrawal time) and adenoma detection rate.⁵⁷ Withdrawal time is directly correlated with adenoma detection, and a 6-minute minimum withdrawal time is recommended in screening colonoscopy examinations of patients at average risk when no polyps are found.⁵⁸ The adenoma detection rate is the strongest evidence-based metric, as each 1% increase in the adenoma detection rate over 19% is associated with a 3% decrease in the risk of colorectal cancer and a 5% decrease in death rate.⁵⁹ The average-risk screening adenoma detection rate differs based on sex: the rate is greater than 20% for women and greater than 30% for men.

Complications from screening, diagnostic, or therapeutic colonoscopy are infrequent but include perforation (4/10,000) and significant intestinal bleeding (8/10,000).^56–62

Patients with a first-degree relative under age 60 with advanced adenomas or colorectal cancer are considered at high risk and should begin screening colonoscopy at age 40, with repeat colonoscopy at 5-year intervals, given a trend toward advanced neoplasia detection compared with FIT.⁶³

Guidelines recently published by the Canadian Association of Gastroenterology and endorsed by the American Gastroenterological Association also support starting screening in high-risk individuals at age 40, with a surveillance interval of 5 to 10 years based on the number of first-degree relatives with colorectal cancer or adenomas.⁶⁴ Consensus statements were based on retrospective cohort, prospective case-controlled, and cross-sectional studies comparing the risk of colorectal cancer in individuals with a family history against those without a family history.

Randomized clinical trials comparing colonoscopy and FIT are under way. Interim analysis of a European trial in which asymptomatic adults ages 50 to 69 were randomized to 1-time colonoscopy (26,703 patients) vs FIT every 2 years (26,599 patients) found significantly higher participation rates in the FIT arm (34.2% vs 24.6%) but higher rates of nonadvanced adenomas (4.2% vs 0.4%) and advanced neoplasia (1.9% vs 0.9%) in the colonoscopy arm.⁶⁵ Cancer was detected in 0.1% in each arm. These findings correlate with those of another study showing higher participation with FIT but higher advanced neoplasia detection rates with colonoscopy.⁶⁶

Detection of precursor lesions is vital, as removing neoplasms is the main strategy to reduce colorectal cancer incidence. Accordingly, the advantage of colonoscopy was illustrated by a study that determined that 53 patients would need to undergo screening colonoscopy to detect 1 advanced adenoma or cancerous lesion, compared with 264 for FIT.⁶⁷

STARTING SCREEING AT AGE 45

The American Cancer Society recently provided a qualified recommendation to start colorectal cancer screening in all individuals at age 45 rather than 50.⁹ This recommendation was based on modeling studies demonstrating that starting screening at age 45 with colonoscopy every 10 years resulted in 25 life-years gained at the cost of 610 colonoscopies per 1,000 individuals. Alternative strategies included FIT, which resulted in an additional 26 life-years gained per 1,000 individuals screened, flexible sigmoidoscopy (23 life-years gained), and computed tomographic colonoscopy (22 life-years gained).

Rates of colorectal cancer are rising in adults under age 50, and 10,000 new cases are anticipated this year.^2,3 Currently, 22 million US adults are between the ages of 45 and 50. The system and support needed to perform screening in all adults over age 45 and a lack of direct evidence to support its benefits in the young population need to be considered before widespread acceptance of the American Cancer Society recommendations. However, if screening is considered, FIT with or without sigmoidoscopy may be appropriate, given that most cancers diagnosed in individuals under age 50 are left-sided.^4,5

Screening has not been proven to reduce all-cause mortality. Randomized controlled trials of FOBT and observational studies of colonoscopy show that screening reduces cancer incidence and mortality. Until the currently ongoing randomized controlled trials comparing colonoscopy with FIT are completed, their comparative impact on colorectal cancer end points is unknown.

PATIENT ADHERENCE IS KEY

FIT and colonoscopy are the most prevalent screening methods in the United States. Careful attention should be given to offer the screening option the patient is most likely to complete, as adherence is key to the benefit from colorectal cancer screening.

The National Colorectal Cancer Roundtable (nccrt.org), established in 1997 by the American Cancer Society and the US Centers for Disease Control and Prevention, is a national coalition of public and private organizations dedicated to reducing colorectal cancer incidence and mortality. The Roundtable waged a national campaign to achieve a colorectal cancer screening rate of 80% in eligible adults by 2018, a goal that was not met. Still, the potential for a substantial impact is a compelling reason to endorse adherence to colorectal cancer screening. The Roundtable provides many resources for physicians to enhance screening in their practice.

The United States has seen a steady decline in colorectal cancer incidence and mortality, mainly as a result of screening. Colorectal cancer is preventable with ensuring patients’ adherence to screening. Screening rates have been shown to increase with patient-provider dialogue and with selection of a screening program the patient prefers and is most likely to complete.

Screening can help prevent colorectal cancer. The United States has seen a steady decline in colorectal cancer incidence and mortality, thanks in large part to screening. Screening rates can be increased with good patient-physician dialogue and by choosing a method the patient prefers and is most likely to complete.

In this article, we review a general approach to screening, focusing on the most commonly used methods in the United States, ie, the guaiac-based fecal occult blood test (FOBT), the fecal immunochemical test (FIT), and colonoscopy. We discuss current colorectal cancer incidence rates, screening recommendations, and how to choose the appropriate screening test.

This article does not discuss patients at high risk of polyps or cancer due to hereditary colon cancer syndromes, a personal history of colorectal neoplasia, inflammatory bowel disease, or primary sclerosing cholangitis.

TRENDS IN INCIDENCE

Colorectal cancer is the second most common type of cancer and cause of cancer-related deaths in the United States, responsible for an estimated 50,000 deaths in 2017. The lifetime risk of its occurrence is estimated to be 1 in 21 men and 1 in 23 women.¹ Encouragingly, the incidence has declined by 24% over the last 30 years,² and by 3% per year from 2004 to 2013.¹ Also, as a result of screening and advances in treatment, 5-year survival rates for patients with colorectal cancer have increased, from 48.6% in 1975 to 66.4% in 2009.²

When detected at a localized stage, the 5-year survival rate in colorectal cancer is greater than 90%. Unfortunately, it is diagnosed early in only 39% of patients. And despite advances in treatment and a doubling of the 5-year survival rate in patients with advanced cancers since 1990,³ the latter is only 14%. In most patients, cancer is diagnosed when it has spread to the lymph nodes (36%) or to distant organs (22%), and the survival rate declines to 71% after lymph-node spread, and 14% after metastasis to distant organs.

It is essential to screen people who have no symptoms, as symptoms such as gastrointestinal bleeding, unexplained abdominal pain or weight loss, a persistent change in bowel movements, and bowel obstruction typically do not arise until the disease is advanced and less amenable to cure.

Increasing prevalence in younger adults

Curiously, the incidence of colorectal cancer is increasing in white US adults under age 50. Over the last 30 years, incidence rates have increased from 1.0% to 2.4% annually in adults ages 20 to 39.⁴ Based on current trends, colon cancer rates are expected to increase by 90% for patients ages 20 to 34 and by 28% for patients 35 to 49 by 2030.⁵

Although recommendations vary for colorectal cancer screening in patients under age 50, clinicians should investigate symptoms such as rectal bleeding, unexplained iron deficiency anemia, progressive abdominal pain, and persistent changes in bowel movements.

Other challenges

Despite the benefits of screening, it is underutilized. Although rates of compliance with screening recommendations have increased 10% over the last 10 years, only 65% of eligible adults currently comply.^1,6

Additionally, certain areas of the country such as Appalachia and the Mississippi Delta have not benefited from the decline in the national rate of colorectal cancer.⁷

SCREENING GUIDELINES

Most guidelines say that colorectal cancer screening should begin at age 50 in people at average risk with no symptoms. However, the American College of Gastroenterology (ACG) recommends beginning screening at age 45 in African Americans, as this group has higher incidence and mortality rates of colorectal cancer.⁸ Also, the American Cancer Society recently recommended beginning screening at age 45 for all individuals.⁹

Screening can stop at age 75 for most patients, according to the ACG,⁸ the US Multi-Society Task Force on Colorectal Cancer,¹⁰ and the US Preventive Services Task Force  (USPSTF).¹¹ However, the decision should be individualized for patients ages 76 to 85. Patients within that age group who are in good health and have not previously been screened are more likely to benefit than those who have previously been screened and had a negative screening test. Patients over age 85 should not begin or continue screening, because of diminished benefit of screening in this age group, shorter life expectancy, advanced comorbid conditions, and the risks of colonoscopy and cancer treatment.

Patients and clinicians are encouraged to collaborate in deciding which screening method is appropriate. Patients adhere better when they are given a choice in the matter.^12–14 And adherence is the key to effective colorectal cancer screening.

Familiarity with the key characteristics of currently available colorectal cancer screening tests will facilitate discussion with patients.

Opportunistic vs programmatic screening

Screening can be classified according to the approach to the patient or population and the intent of the test. Most screening in the United States is opportunistic rather than programmatic—that is, the physician offers the patient screening at the point of service without systematic follow-up or patient re-engagement.

In a programmatic approach, the patient is offered screening through an organized program that streamlines services, reduces overscreening, and provides systematic follow-up of testing.

Stool studies such as FOBT and FIT do not reliably detect cancer precursors such as adenomas and serrated neoplasms. If an FOBT is positive, follow-up diagnostic colonoscopy is required. Unlike screening colonoscopy, diagnostic colonoscopy requires a copayment for Medicare patients, and this should be explained to the patient.

FIT and FOBT detect hemolyzed blood within a stool sample, FOBT by a chemical reaction, and FIT by detecting a globin-specific antibody. Colorectal cancer and some large adenomatous polyps may intermittently bleed and result in occult blood in the stool, iron deficiency anemia, or hematochezia.¹⁵

Fecal occult blood testing

Historically, FOBT was the stool test of choice for screening. It uses an indirect enzymatic reaction to detect hemolyzed blood in the stool. When a specimen containing hemoglobin is added to guaiac paper and a drop of hydrogen peroxide is added to “develop” it, the peroxidase activity of hemoglobin turns the guaiac blue.

Screening with FOBT involves annual testing of 3 consecutively passed stools from different days; FOBT should not be performed at the time of digital rectal examination or if the patient is having overt rectal, urinary, or menstrual bleeding.

Dietary and medication restrictions before and during the testing period are critical, as red meat contains hemoglobin, and certain vegetables (eg, radishes, turnips, cauliflower, cucumbers) contain peroxidase, all of which can cause a false-positive result. Waiting 3 days after the stool sample is collected to develop it can mitigate the peroxidase activity of vegetables.¹⁶ Vitamin C inhibits heme peroxidase activity and leads to false-negative results. Aspirin and high-dose nonsteroidal anti-inflammatory drugs can promote bleeding throughout the intestinal tract.¹⁷

In randomized controlled trials,^18–21 screening with FOBT reduced colorectal cancer mortality rates by 15% to 33%. The 30-year follow-up of a large US trial²² found a 32% relative reduction in mortality rates in patients randomized to annual screening, and a 22% relative reduction in those randomized to screening every 2 years. Despite the many possibilities for false-positive results, the specificity for detecting cancer has ranged from 86.7% to 97.3%, and the sensitivity from 37.1% to 79.4%, highlighting the benefit of colorectal cancer screening programs in unscreened populations.^23–26

FIT vs FOBT in current practice

FIT should replace FOBT as the preferred stool screening method. Instead of an enzymatic reaction that can be altered by food or medication, FIT utilizes an antibody specific to human globin to directly detect hemolyzed blood, thus eliminating the need to modify the diet or medications.²⁷ Additionally, only 1 stool specimen is needed, which may explain why the adherence rate was about 20% higher with FIT than with FOBT in most studies.^28–30

FIT has a sensitivity of 69% to 86% for colorectal cancer and a specificity of 92% to 95%.³¹ The sensitivity can be improved by lowering the threshold value for a positive test, but this is associated with a decrease in specificity. A single FIT has the same sensitivity and specificity as several samples.³²

In a large retrospective US cohort study of programmatic screening with FIT, Jensen et al³³ reported that 48% of 670,841 people who were offered testing actually did the test. Of the 48% who participated in the first round and remained eligible, 75% to 86% participated in subsequent rounds over 4 years. Those who had a positive result on FIT were supposed to undergo colonoscopy, but 22% did not.

The US Multi-Society Task Force on Colorectal Cancer³⁴ suggests that FIT-based screening programs aim for a target FIT completion rate of more than 60% and a target colonoscopy completion rate of more than 80% of patients with positive FITs. These benchmarks were derived from adherence rates in international FIT screening studies in average-risk populations.^35–39 (Note that the large US cohort described above³³ did not meet these goals.) Ideally, every patient with a positive FIT should undergo diagnostic colonoscopy, but in reality only 50% to 83% actually do. Methods shown to improve adherence include structured screening programs with routine performance reports, provider feedback, and involvement of patient navigators.^40–42

Accordingly, several aspects of stool-based testing need to be stressed with patients. Understanding that FOBT is recommended yearly is integral for optimal impact on colorectal cancer incidence and mortality rates.

Additionally, patients should be advised to undergo colonoscopy soon after a positive FIT, because delaying colonoscopy could give precancerous lesions time to progress in stage. The acceptable time between a positive FIT and colonoscopy has yet to be determined. However, a retrospective cohort study of 1.26 million screened patients with 107,000 positive FIT results demonstrated that the rates of cancer discovered on colonoscopy were similar when performed within 30 days or up to 10 months after a positive test. Detection rates increased from 3% to 4.8% at 10 months and to 7.9% at 12 months.⁴³

In modeling studies, Meester et al⁴⁴ showed the estimated lifetime risk and mortality rates from colorectal cancer and life-years gained from screening are significantly better when colonoscopy is completed within 2 weeks rather than 1 year after a positive FIT. Each additional month after 2 weeks incrementally affected these outcomes, with a 1.4% increase in cancer mortality. These data suggest that colonoscopy should be done soon after a positive FIT result and at a maximum of 10 months.^43,44

Screening with FOBT is a multistep process for patients that includes receiving the test kit, collecting the sample, preparing it, returning it, undergoing colonoscopy after a positive test, and repeating in 1 year if negative. The screening program should identify patients at average risk in whom screening is appropriate, ensure delivery of the test, verify the quality of collected samples for laboratory testing against the manufacturer’s recommendations, and report results. Report of a positive FOBT result should provide recommendations for follow-up.

Though evidence clearly supports screening annually or biennially (every 2 years) with FOBT, the ideal interval for FIT is undetermined. Modeling studies utilized by the USPSTF and Multi-Society Task Force demonstrate that colonoscopy and annual FIT result in similar life-years gained, while 2 population-based screening programs have demonstrated that a 2- or 3-year interval may be equally efficacious by lowering the threshold for a positive test.^38,45

Randomized controlled trials of screening colonoscopy vs annual and biennial FIT are currently under way. Cost-effectiveness analysis has shown that offering single-sample FITs at more frequent (annual) intervals performs better than multisample testing at less frequent intervals.^45–47

Compared with stool-based screening, colonoscopy has advantages, including a 10-year screening interval if bowel preparation is adequate and the examination shows no neoplasia, the ability to inspect the entire colon, and the ability to diagnose and treat lesions in the same session.

Screening colonoscopy visualizes the entire colon in more than 98% of cases, although it requires adequate bowel preparation for maximal polyp detection. It can be done safely with or without sedation.⁴⁸

While there are no available randomized controlled trial data on the impact of screening colonoscopy on cancer incidence or mortality, extensive case-control and cohort studies consistently show that screening colonoscopy reduces cancer incidence and mortality rates.^49–54 A US Veterans Administration study of more than 32,000 patients reported a 50% reduction in overall colorectal cancer mortality.⁵⁵ In a microsimulation modeling study that assumed 100% adherence, colonoscopy every 10 years and annual FIT in individuals ages 50 to 75 provided similar life-years gained per 1,000 people screened (270 for colonoscopy, 244 for FIT).⁵⁶

Well-established metrics for maximizing the effectiveness and quality of colonoscopy have been established (Table 2). The most important include the mucosa inspection time (withdrawal time) and adenoma detection rate.⁵⁷ Withdrawal time is directly correlated with adenoma detection, and a 6-minute minimum withdrawal time is recommended in screening colonoscopy examinations of patients at average risk when no polyps are found.⁵⁸ The adenoma detection rate is the strongest evidence-based metric, as each 1% increase in the adenoma detection rate over 19% is associated with a 3% decrease in the risk of colorectal cancer and a 5% decrease in death rate.⁵⁹ The average-risk screening adenoma detection rate differs based on sex: the rate is greater than 20% for women and greater than 30% for men.

Complications from screening, diagnostic, or therapeutic colonoscopy are infrequent but include perforation (4/10,000) and significant intestinal bleeding (8/10,000).^56–62

Patients with a first-degree relative under age 60 with advanced adenomas or colorectal cancer are considered at high risk and should begin screening colonoscopy at age 40, with repeat colonoscopy at 5-year intervals, given a trend toward advanced neoplasia detection compared with FIT.⁶³

Guidelines recently published by the Canadian Association of Gastroenterology and endorsed by the American Gastroenterological Association also support starting screening in high-risk individuals at age 40, with a surveillance interval of 5 to 10 years based on the number of first-degree relatives with colorectal cancer or adenomas.⁶⁴ Consensus statements were based on retrospective cohort, prospective case-controlled, and cross-sectional studies comparing the risk of colorectal cancer in individuals with a family history against those without a family history.

Randomized clinical trials comparing colonoscopy and FIT are under way. Interim analysis of a European trial in which asymptomatic adults ages 50 to 69 were randomized to 1-time colonoscopy (26,703 patients) vs FIT every 2 years (26,599 patients) found significantly higher participation rates in the FIT arm (34.2% vs 24.6%) but higher rates of nonadvanced adenomas (4.2% vs 0.4%) and advanced neoplasia (1.9% vs 0.9%) in the colonoscopy arm.⁶⁵ Cancer was detected in 0.1% in each arm. These findings correlate with those of another study showing higher participation with FIT but higher advanced neoplasia detection rates with colonoscopy.⁶⁶

Detection of precursor lesions is vital, as removing neoplasms is the main strategy to reduce colorectal cancer incidence. Accordingly, the advantage of colonoscopy was illustrated by a study that determined that 53 patients would need to undergo screening colonoscopy to detect 1 advanced adenoma or cancerous lesion, compared with 264 for FIT.⁶⁷

STARTING SCREEING AT AGE 45

The American Cancer Society recently provided a qualified recommendation to start colorectal cancer screening in all individuals at age 45 rather than 50.⁹ This recommendation was based on modeling studies demonstrating that starting screening at age 45 with colonoscopy every 10 years resulted in 25 life-years gained at the cost of 610 colonoscopies per 1,000 individuals. Alternative strategies included FIT, which resulted in an additional 26 life-years gained per 1,000 individuals screened, flexible sigmoidoscopy (23 life-years gained), and computed tomographic colonoscopy (22 life-years gained).

Rates of colorectal cancer are rising in adults under age 50, and 10,000 new cases are anticipated this year.^2,3 Currently, 22 million US adults are between the ages of 45 and 50. The system and support needed to perform screening in all adults over age 45 and a lack of direct evidence to support its benefits in the young population need to be considered before widespread acceptance of the American Cancer Society recommendations. However, if screening is considered, FIT with or without sigmoidoscopy may be appropriate, given that most cancers diagnosed in individuals under age 50 are left-sided.^4,5

Screening has not been proven to reduce all-cause mortality. Randomized controlled trials of FOBT and observational studies of colonoscopy show that screening reduces cancer incidence and mortality. Until the currently ongoing randomized controlled trials comparing colonoscopy with FIT are completed, their comparative impact on colorectal cancer end points is unknown.

PATIENT ADHERENCE IS KEY

FIT and colonoscopy are the most prevalent screening methods in the United States. Careful attention should be given to offer the screening option the patient is most likely to complete, as adherence is key to the benefit from colorectal cancer screening.

The National Colorectal Cancer Roundtable (nccrt.org), established in 1997 by the American Cancer Society and the US Centers for Disease Control and Prevention, is a national coalition of public and private organizations dedicated to reducing colorectal cancer incidence and mortality. The Roundtable waged a national campaign to achieve a colorectal cancer screening rate of 80% in eligible adults by 2018, a goal that was not met. Still, the potential for a substantial impact is a compelling reason to endorse adherence to colorectal cancer screening. The Roundtable provides many resources for physicians to enhance screening in their practice.

The United States has seen a steady decline in colorectal cancer incidence and mortality, mainly as a result of screening. Colorectal cancer is preventable with ensuring patients’ adherence to screening. Screening rates have been shown to increase with patient-provider dialogue and with selection of a screening program the patient prefers and is most likely to complete.

The prevalence of gallstones is approximately 10% to 15% of the adult US population.^1,2 Most cases are asymptomatic, as gallstones are usually discovered incidentally during routine imaging for other abdominal conditions, and only about 20% of patients with asymptomatic gallstones develop clinically significant complications.^2,3

Nevertheless, gallstones carry significant healthcare costs. In 2004, the median inpatient cost for any gallstone-related disease was $11,584, with an overall annual cost of $6.2 billion.^4,5

Laparoscopic cholecystectomy is the standard treatment for symptomatic cholelithiasis. For asymptomatic cholelithasis, the usual approach is expectant management (“watch and wait”), but prophylactic cholecystectomy may be an option in certain patients at high risk.

CHEMICAL COMPOSITION

Gallstones can be classified into 2 main categories based on their predominant chemical composition: cholesterol or pigment.

Cholesterol gallstones

About 75% of gallstones are composed of cholesterol.^3,4 In the past, this type of stone was thought to be caused by gallbladder inflammation, bile stasis, and absorption of bile salts from damaged mucosa. However, it is now known that cholesterol gallstones are the result of biliary supersaturation caused by cholesterol hypersecretion into the gallbladder, gallbladder hypomotility, accelerated cholesterol nucleation and crystallization, and mucin gel accumulation.

Pigment gallstones

Black pigment gallstones account for 10% to 15% of all gallstones.⁶ They are caused by chronic hemolysis in association with supersaturation of bile with calcium hydrogen bilirubinate, along with deposition of calcium carbonate, phosphate, and inorganic salts.⁷

Brown pigment stones, accounting for 5% to 10% of all gallstones,⁶ are caused by infection in the obstructed bile ducts, where bacteria that produce beta-glucuronidase, phospholipase, and slime contribute to formation of the stone.^8,9

RISK FACTORS FOR GALLSTONES

Age. After age 40, the risk increases dramatically, with an incidence 4 times higher for those ages 40 to 69 than in younger people.¹⁰

Female sex. Women of reproductive age are 4 times more likely to develop gallstones than men, but this gap narrows after menopause.¹¹ The higher risk is attributed to female sex hormones, pregnancy, and oral contraceptive use. Estrogen decreases secretion of bile salts and increases secretion of cholesterol into the gallbladder, which leads to cholesterol supersaturation. Progesterone acts synergistically by causing hypomobility of the gallbladder, which in turn leads to bile stasis.^12,13

Ethnicity. The risk is higher in Mexican Americans and Native Americans than in other ethnic groups.¹⁴

Rapid weight loss, such as after bariatric surgery, occurs from decreased caloric intake and promotes bile stasis, while lipolysis increases cholesterol mobilization and secretion into the gallbladder. This creates an environment conducive to bile supersaturation with cholesterol, leading to gallstone formation.

Chronic hemolytic disorders carry an increased risk of developing calcium bilirubinate stones due to increased excretion of bilirubin during hemolysis.

Obesity and diabetes mellitus are both attributed to insulin resistance. Obesity also increases bile stasis and cholesterol saturation.

Most patients with gallstones (cholelithiasis) experience no symptoms. Their gallstones are often discovered incidentally during imaging tests for unrelated or unexplained abdominal symptoms. Most patients with asymptomatic gallstones remain symptom-free, while about 20% develop gallstone-related symptoms.^2,3

Abdominal pain is the most common symptom. The phrase biliary colic—suggesting pain that is fluctuating in nature—appears ubiquitously in the medical literature, but it does not correctly characterize the pain associated with gallstones.

Most patients with gallstone symptoms describe a constant and often severe pain in the right upper abdomen, epigastrium, or both, often persisting for 30 to 120 minutes. Symptoms are frequently reported in the epigastrium when only visceral pain fibers are stimulated due to gallbladder distention. This is usually called midline pain; however, pain occurs in the back and right shoulder in up to 60% of patients, with involvement of somatic fibers.^15,16 Gallstone pain is not relieved by change of position or passage of stool or gas.

Onset of symptoms more than an hour after eating or in the late evening or at night also  very strongly suggests biliary pain. Patients with a history of biliary pain are more likely to experience it again, with a 69% chance of developing recurrent pain within 2 years.¹⁷

GALLSTONE-RELATED COMPLICATIONS

Acute gallbladder inflammation (cholecystitis)

Gallbladder inflammation (cholecystitis) is the most common complication, occurring in up to 10% of symptomatic cases. Many patients with acute cholecystitis present with right upper quadrant pain that may be accompanied by anorexia, nausea, or vomiting. Inspiratory arrest on deep palpation of the right upper quadrant (Murphy sign) has a specificity of 79% to 96% for acute cholecystitis.²⁰ Markers of systemic inflammation such as fever, elevated white blood cell count, and elevated C-reactive protein are highly suggestive of acute cholecystitis.^20,21

Bile duct stones (choledocholithiasis)

Bile duct stones (choledocholithiasis) are detected in 3.4% to 12% of patients with gallstones.^22,23 Most stones in the common bile duct migrate there from the gallbladder via the cystic duct. Less commonly, primary duct stones form in the duct due to biliary stasis. Removing the gallbladder does not completely eliminate the risk of bile duct stones, as stones can remain or recur after surgery.

Bile duct stones can obstruct the common bile duct, which disrupts normal bile flow and leads to jaundice. Other symptoms may include pruritus, right upper quadrant pain, nausea, and vomiting. Serum levels of bilirubin, aspartate aminotransferase, alanine aminotransferase (ALT), and alkaline phosphatase are usually high.²⁴

Acute bacterial infection (cholangitis)

Acute bacterial infection of the biliary system (cholangitis) is usually associated with obstruction of the common bile duct. Common symptoms of acute cholangitis include right upper quadrant pain, fever, and jaundice (Charcot triad), and these are present in about 50% to 75% of cases.²¹ In severe cases, patients can develop altered mental status and septicemic shock in addition to the Charcot triad, a condition called the Reynold pentad. White blood cell counts and serum levels of C-reactive protein, bilirubin, aminotransferases, and alkaline phosphatase are usually elevated.²¹

Pancreatitis

Approximately 4% to 8% of patients with gallstones develop inflammation of the pancreas (pancreatitis).²⁵ The diagnosis of acute pancreatitis requires at least 2 of the following:^26,27

• Abdominal pain (typically epigastric, often radiating to the back)
• Amylase or lipase levels at least 3 times above the normal limit
• Imaging findings that suggest acute pancreatitis.

Gallstone-related pancreatitis should be considered if the ALT level is greater than 150 U/mL, which has a 97% specificity for gallstone-related pancreatitis.²⁸

Transabdominal ultrasonography, with a sensitivity of 84% to 89% and a specificity of up to 99%, is the test of choice for detecting gallstones.²⁹ The characteristic findings of acute cholecystitis on ultrasonography include enlargement of the gallbladder, thickening of the gallbladder wall, presence of pericholecystic fluid, and tenderness elicited by the ultrasound probe over the gallbladder (sonographic Murphy sign).

Scintigraphy as a second test

Acute cholecystitis is primarily a clinical diagnosis and typically does not require additional imaging beyond ultrasonography. When there is discordance between clinical and ultrasonographic findings, the most accurate second imaging test is scintigraphy of the biliary tract, usually performed with technetium-labeled hydroxy iminodiacetic acid. Given intravenously, the radionuclide is rapidly taken up by the liver and then secreted into the bile. In acute cholecystitis, the cystic duct is functionally occluded and the isotope does not enter the gallbladder, creating an imaging void compared with a normal appearance.

Scintigraphy is more sensitive than abdominal ultrasonography, with a sensitivity of up to 97% vs 81% to 88%, respectively.^29,30 The tests have about equal specificity.

Even though scintigraphy is more sensitive, abdominal ultrasonography is often the initial test for patients with suspected acute cholecystitis because it is more widely available, takes less time, does not involve radiation exposure, and can assess for the presence or absence of gallstones and dilation of the intra- and extrahepatic bile ducts.

Looking for stones in the common bile duct

When acute cholangitis due to choledocholithiasis is suspected, abdominal ultrasonography is a prudent initial test to look for gallstones or biliary dilation suggesting obstruction by stones in the common bile duct. Abdominal ultrasonography has only a 22% to 55% sensitivity for visualizing stones in the common bile duct, but it has a 77% to 87% sensitivity for detecting common bile duct dilation, a surrogate marker of stones.³¹

The normal bile duct diameter ranges from 3 to 6 mm, although mild dilation is often seen in older patients or after cholecystectomy or Roux-en-Y gastric bypass surgery.^32,33 Bile duct dilation of up to 10 mm can be considered normal in patients after cholecystectomy.³⁴ A normal-appearing bile duct on ultrasonography has a negative predictive value of 95% for excluding common bile duct stones.³¹

Endoscopic ultrasonography (EUS), magnetic resonance cholangiopancreatography (MRCP), and endoscopic retrograde cholangiopancreatography (ERCP) have similar sensitivity (89%–94%, 85%–92%, and 89%–93%, respectively) and specificity (94%–95%, 93%–97%, and 100%, respectively) for detecting common bile duct stones.^35–37 EUS is superior to MRCP in detecting stones smaller than 6 mm.³⁸

ERCP should be reserved for managing rather than diagnosing common bile duct stones because of the risk of pancreatitis and perforation. Patients undergoing cholecystectomy who are suspected of having choledocholithiasis may undergo intraoperative cholangiography or laparoscopic common bile duct ultrasonography.

WATCH AND WAIT, OR INTERVENE?

Asymptomatic gallstones

Standard treatment for these patients is expectant management. Cholecystectomy is not recommended for patients with asymptomatic gallstones.⁴⁷ Nevertheless, some patients may benefit from prophylactic cholecystectomy. We and others⁴⁸ suggest considering cholecystectomy in the following patients.

Patients with chronic hemolytic anemia (including children with sickle cell anemia and spherocytosis). These patients have a higher risk of developing calcium bilirubinate stones, and cholecystectomy has improved outcomes.⁴⁹ It should be noted that most of these data come from pediatric populations and have been extrapolated to adults.

Native Americans, who have a higher risk of gallbladder cancer if they have gallstones.^2,50

Conversely, calcification of the gallbladder wall (“porcelain gallbladder”) is no longer considered an absolute indication for cholecystectomy. This condition was thought to be associated with a high rate of gallbladder carcinoma, but analyses of larger, more recent data sets found much smaller risks.^51,52 Further, cholecystectomy in these patients was found to be associated with high rates of postoperative complications. Thus, prophylactic cholecystectomy is no longer recommended in asymptomatic cases of porcelain gallbladder.

In addition, concomitant cholecystectomy in patients undergoing bariatric surgery is no longer considered the therapeutic standard. Historically, cholecystectomy was performed in these patients because of the increased risk of gallstones associated with rapid weight loss after surgery. However, research now weighs against concomitant cholecystectomy with bariatric surgery and most other abdominal surgeries for asymptomatic gallstones.⁵³

Based on information in reference 48.

For patients experiencing acute cholecystitis, laparoscopic cholecystectomy within 72 hours is recommended.⁴⁸ There were safety concerns regarding higher rates of morbidity and conversion from laparoscopic to open cholecystectomy in patients who underwent surgery before the acute cholecystitis episode had settled. However, a large meta-analysis found no significant difference between early and delayed laparoscopic cholecystectomy in bile duct injury or conversion rates.⁵⁴ Further, early cholecystectomy—defined as within 1 week of symptom onset—has been found to reduce gallstone-related complications, shorten hospital stays, and lower costs.^55–57 If the patient cannot undergo surgery, percutaneous cholecystotomy or novel endoscopic gallbladder drainage interventions can be used.

Reprinted from ASGE Standards of Practice Committee; Maple JT, Ben-Menachem T, Anderson MA, et al. The role of endoscopy in the evaluation of suspected choledocholithiasis. Gastrointest Endoscp 2010; 71:1–9 with permission from Elsevier.

Several variables predict the presence of bile duct stones in patients who have symptoms (Table 4). Based on these predictors, the ASGE classifies the probabilities as low (< 10%), intermediate (10% to 50%), and high (> 50%)³¹:

• 
  Low-risk patients require no further evaluation of the common bile duct
• High-risk patients should undergo preoperative ERCP and stone extraction if needed
• Intermediate-risk patients should undergo preoperative imaging with EUS or MRCP or intraoperative bile duct evaluation, depending on the availability, costs, and local expertise.

Patients with associated cholangitis should be given intravenous fluids and broad-spectrum antibiotics. Biliary decompression should be done as early as possible to decrease the risk of morbidity and mortality. For acute cholangitis, ERCP is the treatment of choice.²⁵

Patients with acute gallstone pancreatitis should receive conservative management with intravenous isotonic solutions and pain control, followed by laparoscopic cholecystectomy.⁴⁸

The timing of laparoscopic cholecystectomy in acute gallstone pancreatitis has been debated. Studies conducted during the era of open cholecystectomy reported similar or worse outcomes if cholecystectomy was done sooner rather than later.

However, in 1999, Uhl et al⁵⁸ reported that 48 of 77 patients admitted with acute gallstone pancreatitis were able to undergo laparoscopic cholecystectomy during the same admission. Success rates were 85% (30 of 35 patients) in those with mild disease and 62% (8 of 13 patients) in those with severe disease. They concluded laparoscopic cholecystectomy could be safely performed within 7 days in patients with mild disease, whereas in severe disease at least 3 weeks should elapse because of the risk of infection.

In a randomized trial published in 2010, Aboulian et al⁵⁹ reported that hospital length of stay (the primary end point) was shorter in 25 patients who underwent laparoscopic cholecystectomy early (within 48 hours of admission) than in 25 patients who underwent surgery after abdominal pain had resolved and laboratory enzymes showed a normalizing trend, 3.5 vs 5.8 days (P = .0016). Rates of perioperative complications and need for conversion to open surgery were similar between the 2 groups.

If there is associated cholangitis, patients should also be given broad-spectrum antibiotics and should undergo ERCP within 24 hours of admission.^25–27

SUMMARY

Gallstones are common in US adults. Abdominal ultrasonography is the diagnostic imaging test of choice to detect gallbladder stones and assess for findings suggestive of acute cholecystitis and dilation of the common bile duct. Fortunately, most gallstones are asymptomatic and can usually be managed expectantly. In patients who have symptoms or have gallstone complications, laparoscopic cholecystectomy is the standard of care.

The prevalence of gallstones is approximately 10% to 15% of the adult US population.^1,2 Most cases are asymptomatic, as gallstones are usually discovered incidentally during routine imaging for other abdominal conditions, and only about 20% of patients with asymptomatic gallstones develop clinically significant complications.^2,3

Nevertheless, gallstones carry significant healthcare costs. In 2004, the median inpatient cost for any gallstone-related disease was $11,584, with an overall annual cost of $6.2 billion.^4,5

Laparoscopic cholecystectomy is the standard treatment for symptomatic cholelithiasis. For asymptomatic cholelithasis, the usual approach is expectant management (“watch and wait”), but prophylactic cholecystectomy may be an option in certain patients at high risk.

CHEMICAL COMPOSITION

Gallstones can be classified into 2 main categories based on their predominant chemical composition: cholesterol or pigment.

Cholesterol gallstones

About 75% of gallstones are composed of cholesterol.^3,4 In the past, this type of stone was thought to be caused by gallbladder inflammation, bile stasis, and absorption of bile salts from damaged mucosa. However, it is now known that cholesterol gallstones are the result of biliary supersaturation caused by cholesterol hypersecretion into the gallbladder, gallbladder hypomotility, accelerated cholesterol nucleation and crystallization, and mucin gel accumulation.

Pigment gallstones

Black pigment gallstones account for 10% to 15% of all gallstones.⁶ They are caused by chronic hemolysis in association with supersaturation of bile with calcium hydrogen bilirubinate, along with deposition of calcium carbonate, phosphate, and inorganic salts.⁷

Brown pigment stones, accounting for 5% to 10% of all gallstones,⁶ are caused by infection in the obstructed bile ducts, where bacteria that produce beta-glucuronidase, phospholipase, and slime contribute to formation of the stone.^8,9

RISK FACTORS FOR GALLSTONES

Age. After age 40, the risk increases dramatically, with an incidence 4 times higher for those ages 40 to 69 than in younger people.¹⁰

Female sex. Women of reproductive age are 4 times more likely to develop gallstones than men, but this gap narrows after menopause.¹¹ The higher risk is attributed to female sex hormones, pregnancy, and oral contraceptive use. Estrogen decreases secretion of bile salts and increases secretion of cholesterol into the gallbladder, which leads to cholesterol supersaturation. Progesterone acts synergistically by causing hypomobility of the gallbladder, which in turn leads to bile stasis.^12,13

Ethnicity. The risk is higher in Mexican Americans and Native Americans than in other ethnic groups.¹⁴

Rapid weight loss, such as after bariatric surgery, occurs from decreased caloric intake and promotes bile stasis, while lipolysis increases cholesterol mobilization and secretion into the gallbladder. This creates an environment conducive to bile supersaturation with cholesterol, leading to gallstone formation.

Chronic hemolytic disorders carry an increased risk of developing calcium bilirubinate stones due to increased excretion of bilirubin during hemolysis.

Obesity and diabetes mellitus are both attributed to insulin resistance. Obesity also increases bile stasis and cholesterol saturation.

Most patients with gallstones (cholelithiasis) experience no symptoms. Their gallstones are often discovered incidentally during imaging tests for unrelated or unexplained abdominal symptoms. Most patients with asymptomatic gallstones remain symptom-free, while about 20% develop gallstone-related symptoms.^2,3

Abdominal pain is the most common symptom. The phrase biliary colic—suggesting pain that is fluctuating in nature—appears ubiquitously in the medical literature, but it does not correctly characterize the pain associated with gallstones.

Most patients with gallstone symptoms describe a constant and often severe pain in the right upper abdomen, epigastrium, or both, often persisting for 30 to 120 minutes. Symptoms are frequently reported in the epigastrium when only visceral pain fibers are stimulated due to gallbladder distention. This is usually called midline pain; however, pain occurs in the back and right shoulder in up to 60% of patients, with involvement of somatic fibers.^15,16 Gallstone pain is not relieved by change of position or passage of stool or gas.

Onset of symptoms more than an hour after eating or in the late evening or at night also  very strongly suggests biliary pain. Patients with a history of biliary pain are more likely to experience it again, with a 69% chance of developing recurrent pain within 2 years.¹⁷

GALLSTONE-RELATED COMPLICATIONS

Acute gallbladder inflammation (cholecystitis)

Gallbladder inflammation (cholecystitis) is the most common complication, occurring in up to 10% of symptomatic cases. Many patients with acute cholecystitis present with right upper quadrant pain that may be accompanied by anorexia, nausea, or vomiting. Inspiratory arrest on deep palpation of the right upper quadrant (Murphy sign) has a specificity of 79% to 96% for acute cholecystitis.²⁰ Markers of systemic inflammation such as fever, elevated white blood cell count, and elevated C-reactive protein are highly suggestive of acute cholecystitis.^20,21

Bile duct stones (choledocholithiasis)

Bile duct stones (choledocholithiasis) are detected in 3.4% to 12% of patients with gallstones.^22,23 Most stones in the common bile duct migrate there from the gallbladder via the cystic duct. Less commonly, primary duct stones form in the duct due to biliary stasis. Removing the gallbladder does not completely eliminate the risk of bile duct stones, as stones can remain or recur after surgery.

Bile duct stones can obstruct the common bile duct, which disrupts normal bile flow and leads to jaundice. Other symptoms may include pruritus, right upper quadrant pain, nausea, and vomiting. Serum levels of bilirubin, aspartate aminotransferase, alanine aminotransferase (ALT), and alkaline phosphatase are usually high.²⁴

Acute bacterial infection (cholangitis)

Acute bacterial infection of the biliary system (cholangitis) is usually associated with obstruction of the common bile duct. Common symptoms of acute cholangitis include right upper quadrant pain, fever, and jaundice (Charcot triad), and these are present in about 50% to 75% of cases.²¹ In severe cases, patients can develop altered mental status and septicemic shock in addition to the Charcot triad, a condition called the Reynold pentad. White blood cell counts and serum levels of C-reactive protein, bilirubin, aminotransferases, and alkaline phosphatase are usually elevated.²¹

Pancreatitis

Approximately 4% to 8% of patients with gallstones develop inflammation of the pancreas (pancreatitis).²⁵ The diagnosis of acute pancreatitis requires at least 2 of the following:^26,27

• Abdominal pain (typically epigastric, often radiating to the back)
• Amylase or lipase levels at least 3 times above the normal limit
• Imaging findings that suggest acute pancreatitis.

Gallstone-related pancreatitis should be considered if the ALT level is greater than 150 U/mL, which has a 97% specificity for gallstone-related pancreatitis.²⁸

Transabdominal ultrasonography, with a sensitivity of 84% to 89% and a specificity of up to 99%, is the test of choice for detecting gallstones.²⁹ The characteristic findings of acute cholecystitis on ultrasonography include enlargement of the gallbladder, thickening of the gallbladder wall, presence of pericholecystic fluid, and tenderness elicited by the ultrasound probe over the gallbladder (sonographic Murphy sign).

Scintigraphy as a second test

Acute cholecystitis is primarily a clinical diagnosis and typically does not require additional imaging beyond ultrasonography. When there is discordance between clinical and ultrasonographic findings, the most accurate second imaging test is scintigraphy of the biliary tract, usually performed with technetium-labeled hydroxy iminodiacetic acid. Given intravenously, the radionuclide is rapidly taken up by the liver and then secreted into the bile. In acute cholecystitis, the cystic duct is functionally occluded and the isotope does not enter the gallbladder, creating an imaging void compared with a normal appearance.

Scintigraphy is more sensitive than abdominal ultrasonography, with a sensitivity of up to 97% vs 81% to 88%, respectively.^29,30 The tests have about equal specificity.

Even though scintigraphy is more sensitive, abdominal ultrasonography is often the initial test for patients with suspected acute cholecystitis because it is more widely available, takes less time, does not involve radiation exposure, and can assess for the presence or absence of gallstones and dilation of the intra- and extrahepatic bile ducts.

Looking for stones in the common bile duct

When acute cholangitis due to choledocholithiasis is suspected, abdominal ultrasonography is a prudent initial test to look for gallstones or biliary dilation suggesting obstruction by stones in the common bile duct. Abdominal ultrasonography has only a 22% to 55% sensitivity for visualizing stones in the common bile duct, but it has a 77% to 87% sensitivity for detecting common bile duct dilation, a surrogate marker of stones.³¹

The normal bile duct diameter ranges from 3 to 6 mm, although mild dilation is often seen in older patients or after cholecystectomy or Roux-en-Y gastric bypass surgery.^32,33 Bile duct dilation of up to 10 mm can be considered normal in patients after cholecystectomy.³⁴ A normal-appearing bile duct on ultrasonography has a negative predictive value of 95% for excluding common bile duct stones.³¹

Endoscopic ultrasonography (EUS), magnetic resonance cholangiopancreatography (MRCP), and endoscopic retrograde cholangiopancreatography (ERCP) have similar sensitivity (89%–94%, 85%–92%, and 89%–93%, respectively) and specificity (94%–95%, 93%–97%, and 100%, respectively) for detecting common bile duct stones.^35–37 EUS is superior to MRCP in detecting stones smaller than 6 mm.³⁸

ERCP should be reserved for managing rather than diagnosing common bile duct stones because of the risk of pancreatitis and perforation. Patients undergoing cholecystectomy who are suspected of having choledocholithiasis may undergo intraoperative cholangiography or laparoscopic common bile duct ultrasonography.

WATCH AND WAIT, OR INTERVENE?

Asymptomatic gallstones

Standard treatment for these patients is expectant management. Cholecystectomy is not recommended for patients with asymptomatic gallstones.⁴⁷ Nevertheless, some patients may benefit from prophylactic cholecystectomy. We and others⁴⁸ suggest considering cholecystectomy in the following patients.

Patients with chronic hemolytic anemia (including children with sickle cell anemia and spherocytosis). These patients have a higher risk of developing calcium bilirubinate stones, and cholecystectomy has improved outcomes.⁴⁹ It should be noted that most of these data come from pediatric populations and have been extrapolated to adults.

Native Americans, who have a higher risk of gallbladder cancer if they have gallstones.^2,50

Conversely, calcification of the gallbladder wall (“porcelain gallbladder”) is no longer considered an absolute indication for cholecystectomy. This condition was thought to be associated with a high rate of gallbladder carcinoma, but analyses of larger, more recent data sets found much smaller risks.^51,52 Further, cholecystectomy in these patients was found to be associated with high rates of postoperative complications. Thus, prophylactic cholecystectomy is no longer recommended in asymptomatic cases of porcelain gallbladder.

In addition, concomitant cholecystectomy in patients undergoing bariatric surgery is no longer considered the therapeutic standard. Historically, cholecystectomy was performed in these patients because of the increased risk of gallstones associated with rapid weight loss after surgery. However, research now weighs against concomitant cholecystectomy with bariatric surgery and most other abdominal surgeries for asymptomatic gallstones.⁵³

Based on information in reference 48.

For patients experiencing acute cholecystitis, laparoscopic cholecystectomy within 72 hours is recommended.⁴⁸ There were safety concerns regarding higher rates of morbidity and conversion from laparoscopic to open cholecystectomy in patients who underwent surgery before the acute cholecystitis episode had settled. However, a large meta-analysis found no significant difference between early and delayed laparoscopic cholecystectomy in bile duct injury or conversion rates.⁵⁴ Further, early cholecystectomy—defined as within 1 week of symptom onset—has been found to reduce gallstone-related complications, shorten hospital stays, and lower costs.^55–57 If the patient cannot undergo surgery, percutaneous cholecystotomy or novel endoscopic gallbladder drainage interventions can be used.

Reprinted from ASGE Standards of Practice Committee; Maple JT, Ben-Menachem T, Anderson MA, et al. The role of endoscopy in the evaluation of suspected choledocholithiasis. Gastrointest Endoscp 2010; 71:1–9 with permission from Elsevier.

Several variables predict the presence of bile duct stones in patients who have symptoms (Table 4). Based on these predictors, the ASGE classifies the probabilities as low (< 10%), intermediate (10% to 50%), and high (> 50%)³¹:

• 
  Low-risk patients require no further evaluation of the common bile duct
• High-risk patients should undergo preoperative ERCP and stone extraction if needed
• Intermediate-risk patients should undergo preoperative imaging with EUS or MRCP or intraoperative bile duct evaluation, depending on the availability, costs, and local expertise.

Patients with associated cholangitis should be given intravenous fluids and broad-spectrum antibiotics. Biliary decompression should be done as early as possible to decrease the risk of morbidity and mortality. For acute cholangitis, ERCP is the treatment of choice.²⁵

Patients with acute gallstone pancreatitis should receive conservative management with intravenous isotonic solutions and pain control, followed by laparoscopic cholecystectomy.⁴⁸

The timing of laparoscopic cholecystectomy in acute gallstone pancreatitis has been debated. Studies conducted during the era of open cholecystectomy reported similar or worse outcomes if cholecystectomy was done sooner rather than later.

However, in 1999, Uhl et al⁵⁸ reported that 48 of 77 patients admitted with acute gallstone pancreatitis were able to undergo laparoscopic cholecystectomy during the same admission. Success rates were 85% (30 of 35 patients) in those with mild disease and 62% (8 of 13 patients) in those with severe disease. They concluded laparoscopic cholecystectomy could be safely performed within 7 days in patients with mild disease, whereas in severe disease at least 3 weeks should elapse because of the risk of infection.

In a randomized trial published in 2010, Aboulian et al⁵⁹ reported that hospital length of stay (the primary end point) was shorter in 25 patients who underwent laparoscopic cholecystectomy early (within 48 hours of admission) than in 25 patients who underwent surgery after abdominal pain had resolved and laboratory enzymes showed a normalizing trend, 3.5 vs 5.8 days (P = .0016). Rates of perioperative complications and need for conversion to open surgery were similar between the 2 groups.

If there is associated cholangitis, patients should also be given broad-spectrum antibiotics and should undergo ERCP within 24 hours of admission.^25–27

SUMMARY

Gallstones are common in US adults. Abdominal ultrasonography is the diagnostic imaging test of choice to detect gallbladder stones and assess for findings suggestive of acute cholecystitis and dilation of the common bile duct. Fortunately, most gallstones are asymptomatic and can usually be managed expectantly. In patients who have symptoms or have gallstone complications, laparoscopic cholecystectomy is the standard of care.

The prevalence of gallstones is approximately 10% to 15% of the adult US population.^1,2 Most cases are asymptomatic, as gallstones are usually discovered incidentally during routine imaging for other abdominal conditions, and only about 20% of patients with asymptomatic gallstones develop clinically significant complications.^2,3

Nevertheless, gallstones carry significant healthcare costs. In 2004, the median inpatient cost for any gallstone-related disease was $11,584, with an overall annual cost of $6.2 billion.^4,5

Laparoscopic cholecystectomy is the standard treatment for symptomatic cholelithiasis. For asymptomatic cholelithasis, the usual approach is expectant management (“watch and wait”), but prophylactic cholecystectomy may be an option in certain patients at high risk.

CHEMICAL COMPOSITION

Gallstones can be classified into 2 main categories based on their predominant chemical composition: cholesterol or pigment.

Cholesterol gallstones

About 75% of gallstones are composed of cholesterol.^3,4 In the past, this type of stone was thought to be caused by gallbladder inflammation, bile stasis, and absorption of bile salts from damaged mucosa. However, it is now known that cholesterol gallstones are the result of biliary supersaturation caused by cholesterol hypersecretion into the gallbladder, gallbladder hypomotility, accelerated cholesterol nucleation and crystallization, and mucin gel accumulation.

Pigment gallstones

Black pigment gallstones account for 10% to 15% of all gallstones.⁶ They are caused by chronic hemolysis in association with supersaturation of bile with calcium hydrogen bilirubinate, along with deposition of calcium carbonate, phosphate, and inorganic salts.⁷

Brown pigment stones, accounting for 5% to 10% of all gallstones,⁶ are caused by infection in the obstructed bile ducts, where bacteria that produce beta-glucuronidase, phospholipase, and slime contribute to formation of the stone.^8,9

RISK FACTORS FOR GALLSTONES

Age. After age 40, the risk increases dramatically, with an incidence 4 times higher for those ages 40 to 69 than in younger people.¹⁰

Female sex. Women of reproductive age are 4 times more likely to develop gallstones than men, but this gap narrows after menopause.¹¹ The higher risk is attributed to female sex hormones, pregnancy, and oral contraceptive use. Estrogen decreases secretion of bile salts and increases secretion of cholesterol into the gallbladder, which leads to cholesterol supersaturation. Progesterone acts synergistically by causing hypomobility of the gallbladder, which in turn leads to bile stasis.^12,13

Ethnicity. The risk is higher in Mexican Americans and Native Americans than in other ethnic groups.¹⁴

Rapid weight loss, such as after bariatric surgery, occurs from decreased caloric intake and promotes bile stasis, while lipolysis increases cholesterol mobilization and secretion into the gallbladder. This creates an environment conducive to bile supersaturation with cholesterol, leading to gallstone formation.

Chronic hemolytic disorders carry an increased risk of developing calcium bilirubinate stones due to increased excretion of bilirubin during hemolysis.

Obesity and diabetes mellitus are both attributed to insulin resistance. Obesity also increases bile stasis and cholesterol saturation.

Most patients with gallstones (cholelithiasis) experience no symptoms. Their gallstones are often discovered incidentally during imaging tests for unrelated or unexplained abdominal symptoms. Most patients with asymptomatic gallstones remain symptom-free, while about 20% develop gallstone-related symptoms.^2,3

Abdominal pain is the most common symptom. The phrase biliary colic—suggesting pain that is fluctuating in nature—appears ubiquitously in the medical literature, but it does not correctly characterize the pain associated with gallstones.

Most patients with gallstone symptoms describe a constant and often severe pain in the right upper abdomen, epigastrium, or both, often persisting for 30 to 120 minutes. Symptoms are frequently reported in the epigastrium when only visceral pain fibers are stimulated due to gallbladder distention. This is usually called midline pain; however, pain occurs in the back and right shoulder in up to 60% of patients, with involvement of somatic fibers.^15,16 Gallstone pain is not relieved by change of position or passage of stool or gas.

Onset of symptoms more than an hour after eating or in the late evening or at night also  very strongly suggests biliary pain. Patients with a history of biliary pain are more likely to experience it again, with a 69% chance of developing recurrent pain within 2 years.¹⁷

GALLSTONE-RELATED COMPLICATIONS

Acute gallbladder inflammation (cholecystitis)

Gallbladder inflammation (cholecystitis) is the most common complication, occurring in up to 10% of symptomatic cases. Many patients with acute cholecystitis present with right upper quadrant pain that may be accompanied by anorexia, nausea, or vomiting. Inspiratory arrest on deep palpation of the right upper quadrant (Murphy sign) has a specificity of 79% to 96% for acute cholecystitis.²⁰ Markers of systemic inflammation such as fever, elevated white blood cell count, and elevated C-reactive protein are highly suggestive of acute cholecystitis.^20,21

Bile duct stones (choledocholithiasis)

Bile duct stones (choledocholithiasis) are detected in 3.4% to 12% of patients with gallstones.^22,23 Most stones in the common bile duct migrate there from the gallbladder via the cystic duct. Less commonly, primary duct stones form in the duct due to biliary stasis. Removing the gallbladder does not completely eliminate the risk of bile duct stones, as stones can remain or recur after surgery.

Bile duct stones can obstruct the common bile duct, which disrupts normal bile flow and leads to jaundice. Other symptoms may include pruritus, right upper quadrant pain, nausea, and vomiting. Serum levels of bilirubin, aspartate aminotransferase, alanine aminotransferase (ALT), and alkaline phosphatase are usually high.²⁴

Acute bacterial infection (cholangitis)

Acute bacterial infection of the biliary system (cholangitis) is usually associated with obstruction of the common bile duct. Common symptoms of acute cholangitis include right upper quadrant pain, fever, and jaundice (Charcot triad), and these are present in about 50% to 75% of cases.²¹ In severe cases, patients can develop altered mental status and septicemic shock in addition to the Charcot triad, a condition called the Reynold pentad. White blood cell counts and serum levels of C-reactive protein, bilirubin, aminotransferases, and alkaline phosphatase are usually elevated.²¹

Pancreatitis

Approximately 4% to 8% of patients with gallstones develop inflammation of the pancreas (pancreatitis).²⁵ The diagnosis of acute pancreatitis requires at least 2 of the following:^26,27

• Abdominal pain (typically epigastric, often radiating to the back)
• Amylase or lipase levels at least 3 times above the normal limit
• Imaging findings that suggest acute pancreatitis.

Gallstone-related pancreatitis should be considered if the ALT level is greater than 150 U/mL, which has a 97% specificity for gallstone-related pancreatitis.²⁸

Transabdominal ultrasonography, with a sensitivity of 84% to 89% and a specificity of up to 99%, is the test of choice for detecting gallstones.²⁹ The characteristic findings of acute cholecystitis on ultrasonography include enlargement of the gallbladder, thickening of the gallbladder wall, presence of pericholecystic fluid, and tenderness elicited by the ultrasound probe over the gallbladder (sonographic Murphy sign).

Scintigraphy as a second test

Acute cholecystitis is primarily a clinical diagnosis and typically does not require additional imaging beyond ultrasonography. When there is discordance between clinical and ultrasonographic findings, the most accurate second imaging test is scintigraphy of the biliary tract, usually performed with technetium-labeled hydroxy iminodiacetic acid. Given intravenously, the radionuclide is rapidly taken up by the liver and then secreted into the bile. In acute cholecystitis, the cystic duct is functionally occluded and the isotope does not enter the gallbladder, creating an imaging void compared with a normal appearance.

Scintigraphy is more sensitive than abdominal ultrasonography, with a sensitivity of up to 97% vs 81% to 88%, respectively.^29,30 The tests have about equal specificity.

Even though scintigraphy is more sensitive, abdominal ultrasonography is often the initial test for patients with suspected acute cholecystitis because it is more widely available, takes less time, does not involve radiation exposure, and can assess for the presence or absence of gallstones and dilation of the intra- and extrahepatic bile ducts.

Looking for stones in the common bile duct

When acute cholangitis due to choledocholithiasis is suspected, abdominal ultrasonography is a prudent initial test to look for gallstones or biliary dilation suggesting obstruction by stones in the common bile duct. Abdominal ultrasonography has only a 22% to 55% sensitivity for visualizing stones in the common bile duct, but it has a 77% to 87% sensitivity for detecting common bile duct dilation, a surrogate marker of stones.³¹

The normal bile duct diameter ranges from 3 to 6 mm, although mild dilation is often seen in older patients or after cholecystectomy or Roux-en-Y gastric bypass surgery.^32,33 Bile duct dilation of up to 10 mm can be considered normal in patients after cholecystectomy.³⁴ A normal-appearing bile duct on ultrasonography has a negative predictive value of 95% for excluding common bile duct stones.³¹

Endoscopic ultrasonography (EUS), magnetic resonance cholangiopancreatography (MRCP), and endoscopic retrograde cholangiopancreatography (ERCP) have similar sensitivity (89%–94%, 85%–92%, and 89%–93%, respectively) and specificity (94%–95%, 93%–97%, and 100%, respectively) for detecting common bile duct stones.^35–37 EUS is superior to MRCP in detecting stones smaller than 6 mm.³⁸

ERCP should be reserved for managing rather than diagnosing common bile duct stones because of the risk of pancreatitis and perforation. Patients undergoing cholecystectomy who are suspected of having choledocholithiasis may undergo intraoperative cholangiography or laparoscopic common bile duct ultrasonography.

WATCH AND WAIT, OR INTERVENE?

Asymptomatic gallstones

Standard treatment for these patients is expectant management. Cholecystectomy is not recommended for patients with asymptomatic gallstones.⁴⁷ Nevertheless, some patients may benefit from prophylactic cholecystectomy. We and others⁴⁸ suggest considering cholecystectomy in the following patients.

Patients with chronic hemolytic anemia (including children with sickle cell anemia and spherocytosis). These patients have a higher risk of developing calcium bilirubinate stones, and cholecystectomy has improved outcomes.⁴⁹ It should be noted that most of these data come from pediatric populations and have been extrapolated to adults.

Native Americans, who have a higher risk of gallbladder cancer if they have gallstones.^2,50

Conversely, calcification of the gallbladder wall (“porcelain gallbladder”) is no longer considered an absolute indication for cholecystectomy. This condition was thought to be associated with a high rate of gallbladder carcinoma, but analyses of larger, more recent data sets found much smaller risks.^51,52 Further, cholecystectomy in these patients was found to be associated with high rates of postoperative complications. Thus, prophylactic cholecystectomy is no longer recommended in asymptomatic cases of porcelain gallbladder.

In addition, concomitant cholecystectomy in patients undergoing bariatric surgery is no longer considered the therapeutic standard. Historically, cholecystectomy was performed in these patients because of the increased risk of gallstones associated with rapid weight loss after surgery. However, research now weighs against concomitant cholecystectomy with bariatric surgery and most other abdominal surgeries for asymptomatic gallstones.⁵³

Based on information in reference 48.

For patients experiencing acute cholecystitis, laparoscopic cholecystectomy within 72 hours is recommended.⁴⁸ There were safety concerns regarding higher rates of morbidity and conversion from laparoscopic to open cholecystectomy in patients who underwent surgery before the acute cholecystitis episode had settled. However, a large meta-analysis found no significant difference between early and delayed laparoscopic cholecystectomy in bile duct injury or conversion rates.⁵⁴ Further, early cholecystectomy—defined as within 1 week of symptom onset—has been found to reduce gallstone-related complications, shorten hospital stays, and lower costs.^55–57 If the patient cannot undergo surgery, percutaneous cholecystotomy or novel endoscopic gallbladder drainage interventions can be used.

Reprinted from ASGE Standards of Practice Committee; Maple JT, Ben-Menachem T, Anderson MA, et al. The role of endoscopy in the evaluation of suspected choledocholithiasis. Gastrointest Endoscp 2010; 71:1–9 with permission from Elsevier.

Several variables predict the presence of bile duct stones in patients who have symptoms (Table 4). Based on these predictors, the ASGE classifies the probabilities as low (< 10%), intermediate (10% to 50%), and high (> 50%)³¹:

• 
  Low-risk patients require no further evaluation of the common bile duct
• High-risk patients should undergo preoperative ERCP and stone extraction if needed
• Intermediate-risk patients should undergo preoperative imaging with EUS or MRCP or intraoperative bile duct evaluation, depending on the availability, costs, and local expertise.

Patients with associated cholangitis should be given intravenous fluids and broad-spectrum antibiotics. Biliary decompression should be done as early as possible to decrease the risk of morbidity and mortality. For acute cholangitis, ERCP is the treatment of choice.²⁵

Patients with acute gallstone pancreatitis should receive conservative management with intravenous isotonic solutions and pain control, followed by laparoscopic cholecystectomy.⁴⁸

The timing of laparoscopic cholecystectomy in acute gallstone pancreatitis has been debated. Studies conducted during the era of open cholecystectomy reported similar or worse outcomes if cholecystectomy was done sooner rather than later.

However, in 1999, Uhl et al⁵⁸ reported that 48 of 77 patients admitted with acute gallstone pancreatitis were able to undergo laparoscopic cholecystectomy during the same admission. Success rates were 85% (30 of 35 patients) in those with mild disease and 62% (8 of 13 patients) in those with severe disease. They concluded laparoscopic cholecystectomy could be safely performed within 7 days in patients with mild disease, whereas in severe disease at least 3 weeks should elapse because of the risk of infection.

In a randomized trial published in 2010, Aboulian et al⁵⁹ reported that hospital length of stay (the primary end point) was shorter in 25 patients who underwent laparoscopic cholecystectomy early (within 48 hours of admission) than in 25 patients who underwent surgery after abdominal pain had resolved and laboratory enzymes showed a normalizing trend, 3.5 vs 5.8 days (P = .0016). Rates of perioperative complications and need for conversion to open surgery were similar between the 2 groups.

If there is associated cholangitis, patients should also be given broad-spectrum antibiotics and should undergo ERCP within 24 hours of admission.^25–27

SUMMARY

Gallstones are common in US adults. Abdominal ultrasonography is the diagnostic imaging test of choice to detect gallbladder stones and assess for findings suggestive of acute cholecystitis and dilation of the common bile duct. Fortunately, most gallstones are asymptomatic and can usually be managed expectantly. In patients who have symptoms or have gallstone complications, laparoscopic cholecystectomy is the standard of care.