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Yes. Any occult blood on a fecal occult blood test (FOBT) should be investigated further because colorectal cancer mortality decreases when positive FOBT screenings are evaluated (strength of recommendation: A, systematic review, evidence-based guidelines).
Follow-up of positive screening results lowers colorectal cancer mortality
No studies directly compare the need for colonoscopy when various numbers of stool samples are positive for occult blood on an FOBT. However, a Cochrane review of 4 randomized controlled trials (RCTs) with more than 300,000 patients examined the effectiveness of the FOBT for colorectal cancer screening.1 Each study varied in its follow-up approach to a positive FOBT.
Two RCTs offered screening with FOBT or standard care (no screening) and immediately followed up any positive results with a colonoscopy. The screened group had lower colorectal cancer mortality (N=46,551; risk ratio [RR]=0.75; 95% confidence interval [CI], 0.62-0.91) than the unscreened group (N=61,933; RR=0.84; 95% CI, 0.73-0.96).
Another trial screened with FOBT or standard care and offered colonoscopy if 5 or more samples were positive on initial testing or one or more were positive on repeat testing. The screened group showed reduced colorectal cancer mortality (N=152,850; RR=0.87; 95% CI, 0.78-0.97).
The final trial examined screening with FOBT compared with standard care and inconsistently offered repeat FOBT or sigmoidoscopy with double-contrast barium enema if any samples were positive on initial testing, which resulted in decreased colorectal cancer mortality for the screened group (N=68,308; RR=0.84; 95% CI, 0.71-0.99).
Evidence-based guidelines recommend follow-up colonoscopy
Evidence-based guidelines from the United States Preventive Services Task Force, the European Commission, and the Canadian Task Force on Preventive Health Care state that FOBT should be used for colorectal cancer screening and that any positive screening test should be followed up with colonoscopy to further evaluate for neoplasm.2-4
An evidence- and expert opinion-based guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology clarifies the issue further by emphasizing that any positive FOBT necessitates a colonoscopy and stating that repeat FOBT or other test is inappropriate as follow-up.5
1. Hewitson P, Glasziou P, Watson E, et al. Cochrane systematic review of colorectal cancer screening using the fecal occult blood test (hemoccult): an update. Am J Gastroenterol. 2008;103:1541-1549.
2. United States Preventive Services Task Force. Screening for colorectal cancer: US Preventive Services Task Force recommendation statement. Ann Intern Med. 2008;149:627-638.
3. vonKarsa L, Patnick J, Segnan N, eds. European Guidelines for Quality Assurance in Colorectal Cancer Screening and Diagnosis. Luxembourg: Publications Office of the European Union; 2010.
4. McLeod RS; Canadian Task Force on Preventive Health Care. Screening strategies for colorectal cancer: a systematic review of the evidence. Can J Gastroenterol. 2001;15:647-660.
5. Levin B, Lieberman DA, McFarland B, et al. Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology. Gastroenterology. 2008;134:1570-1595.
Yes. Any occult blood on a fecal occult blood test (FOBT) should be investigated further because colorectal cancer mortality decreases when positive FOBT screenings are evaluated (strength of recommendation: A, systematic review, evidence-based guidelines).
Follow-up of positive screening results lowers colorectal cancer mortality
No studies directly compare the need for colonoscopy when various numbers of stool samples are positive for occult blood on an FOBT. However, a Cochrane review of 4 randomized controlled trials (RCTs) with more than 300,000 patients examined the effectiveness of the FOBT for colorectal cancer screening.1 Each study varied in its follow-up approach to a positive FOBT.
Two RCTs offered screening with FOBT or standard care (no screening) and immediately followed up any positive results with a colonoscopy. The screened group had lower colorectal cancer mortality (N=46,551; risk ratio [RR]=0.75; 95% confidence interval [CI], 0.62-0.91) than the unscreened group (N=61,933; RR=0.84; 95% CI, 0.73-0.96).
Another trial screened with FOBT or standard care and offered colonoscopy if 5 or more samples were positive on initial testing or one or more were positive on repeat testing. The screened group showed reduced colorectal cancer mortality (N=152,850; RR=0.87; 95% CI, 0.78-0.97).
The final trial examined screening with FOBT compared with standard care and inconsistently offered repeat FOBT or sigmoidoscopy with double-contrast barium enema if any samples were positive on initial testing, which resulted in decreased colorectal cancer mortality for the screened group (N=68,308; RR=0.84; 95% CI, 0.71-0.99).
Evidence-based guidelines recommend follow-up colonoscopy
Evidence-based guidelines from the United States Preventive Services Task Force, the European Commission, and the Canadian Task Force on Preventive Health Care state that FOBT should be used for colorectal cancer screening and that any positive screening test should be followed up with colonoscopy to further evaluate for neoplasm.2-4
An evidence- and expert opinion-based guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology clarifies the issue further by emphasizing that any positive FOBT necessitates a colonoscopy and stating that repeat FOBT or other test is inappropriate as follow-up.5
Yes. Any occult blood on a fecal occult blood test (FOBT) should be investigated further because colorectal cancer mortality decreases when positive FOBT screenings are evaluated (strength of recommendation: A, systematic review, evidence-based guidelines).
Follow-up of positive screening results lowers colorectal cancer mortality
No studies directly compare the need for colonoscopy when various numbers of stool samples are positive for occult blood on an FOBT. However, a Cochrane review of 4 randomized controlled trials (RCTs) with more than 300,000 patients examined the effectiveness of the FOBT for colorectal cancer screening.1 Each study varied in its follow-up approach to a positive FOBT.
Two RCTs offered screening with FOBT or standard care (no screening) and immediately followed up any positive results with a colonoscopy. The screened group had lower colorectal cancer mortality (N=46,551; risk ratio [RR]=0.75; 95% confidence interval [CI], 0.62-0.91) than the unscreened group (N=61,933; RR=0.84; 95% CI, 0.73-0.96).
Another trial screened with FOBT or standard care and offered colonoscopy if 5 or more samples were positive on initial testing or one or more were positive on repeat testing. The screened group showed reduced colorectal cancer mortality (N=152,850; RR=0.87; 95% CI, 0.78-0.97).
The final trial examined screening with FOBT compared with standard care and inconsistently offered repeat FOBT or sigmoidoscopy with double-contrast barium enema if any samples were positive on initial testing, which resulted in decreased colorectal cancer mortality for the screened group (N=68,308; RR=0.84; 95% CI, 0.71-0.99).
Evidence-based guidelines recommend follow-up colonoscopy
Evidence-based guidelines from the United States Preventive Services Task Force, the European Commission, and the Canadian Task Force on Preventive Health Care state that FOBT should be used for colorectal cancer screening and that any positive screening test should be followed up with colonoscopy to further evaluate for neoplasm.2-4
An evidence- and expert opinion-based guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology clarifies the issue further by emphasizing that any positive FOBT necessitates a colonoscopy and stating that repeat FOBT or other test is inappropriate as follow-up.5
1. Hewitson P, Glasziou P, Watson E, et al. Cochrane systematic review of colorectal cancer screening using the fecal occult blood test (hemoccult): an update. Am J Gastroenterol. 2008;103:1541-1549.
2. United States Preventive Services Task Force. Screening for colorectal cancer: US Preventive Services Task Force recommendation statement. Ann Intern Med. 2008;149:627-638.
3. vonKarsa L, Patnick J, Segnan N, eds. European Guidelines for Quality Assurance in Colorectal Cancer Screening and Diagnosis. Luxembourg: Publications Office of the European Union; 2010.
4. McLeod RS; Canadian Task Force on Preventive Health Care. Screening strategies for colorectal cancer: a systematic review of the evidence. Can J Gastroenterol. 2001;15:647-660.
5. Levin B, Lieberman DA, McFarland B, et al. Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology. Gastroenterology. 2008;134:1570-1595.
1. Hewitson P, Glasziou P, Watson E, et al. Cochrane systematic review of colorectal cancer screening using the fecal occult blood test (hemoccult): an update. Am J Gastroenterol. 2008;103:1541-1549.
2. United States Preventive Services Task Force. Screening for colorectal cancer: US Preventive Services Task Force recommendation statement. Ann Intern Med. 2008;149:627-638.
3. vonKarsa L, Patnick J, Segnan N, eds. European Guidelines for Quality Assurance in Colorectal Cancer Screening and Diagnosis. Luxembourg: Publications Office of the European Union; 2010.
4. McLeod RS; Canadian Task Force on Preventive Health Care. Screening strategies for colorectal cancer: a systematic review of the evidence. Can J Gastroenterol. 2001;15:647-660.
5. Levin B, Lieberman DA, McFarland B, et al. Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology. Gastroenterology. 2008;134:1570-1595.
Evidence-based answers from the Family Physicians Inquiries Network