Screening Mammography: Debates, Guidelines, Issues

The screening mammography debate has been rekindled by the American Cancer Society’s updated guideline released in October 2015. Surgeons are now looking at yet another iteration of the optimal surveillance schedule aimed at reducing breast cancer mortality.

Nearly all breast cancer patients undergo surgery as at least one component of their care through diagnostic biopsy and/or definitive locoregional management, and many women are referred to surgeons for evaluation as well as follow-up for a variety of benign breast problems. The discussion of breast cancer screening with patients can be complicated by the many guidelines with conflicting recommendations, not to mention patient fears triggered by incompletely informed or simplistic media coverage. Surgeons are therefore obliged to remain knowledgeable regarding the status and rationale for breast cancer screening guidelines that have been developed by our colleagues in the American Cancer Society as well as other organizations.

Context of the updated guideline

The American Cancer Society and the American College of Surgeons have historically advocated in favor of annual screening mammography for average-risk women in the United States beginning at age 40 years (https://goo.gl/4W92EI). In 2009, the United States Preventive Services Task Force (USPSTF) published a recommendation that women delay initiation of screening mammography until reaching age 50, with follow-up studies performed biennially thereafter. This USPSTF guideline has remain unchanged as of 2015 (http://goo.gl/RYYWEP). Other medical societies and institutions have established their own guidelines.

The updated American Cancer Society guideline now recommends that average-risk women initiate annual mammography at age 45, but advocates in favor of availability of annual mammography beginning at age 40; the updated guideline also indicates that women can transition to biennial mammography at age 55, but should have access to continued annual mammography in accordance with personal preferences and after consideration of risks and benefits (JAMA. 2015;314[15]:1599-614).

The updated guideline can basically be interpreted as a more relaxed version of the prior guideline, which featured a straightforward mandate for average-risk women to undergo annual screening mammography beginning at age 40 years. However, the increased complexity of the more flexible guideline has generated legitimate concerns regarding the potential for confusion and misinterpretation.

Updated guideline rationale and empirical basis

The Society commissioned a systematic review to evaluate the benefits and harms of mammographic screening as well as clinical breast examination, based upon randomized clinical trials, and observational and modeling studies (JAMA. 2015;314[15]: 1615-34).

The Society then convened their Guideline Development Group (GDG) and GDG Breast Subgroup to interpret the systematic review for the purpose of drafting the breast cancer screening update. This process was further guided by a panel of External Expert Advisors. Mortality reductions were analyzed in the context of population-based breast cancer incidence rates by 5-year age increments.

Not surprisingly, the overall review confirmed the findings of several published studies that screening mammography in women aged 40-79 reduces breast cancer mortality rates by 20%-50%, with extent of benefit varying by age, as well as study design (randomized clinical trial versus observational). Since breast cancer incidence rates increase substantially among women by age (incidence rates per 100,000 population for women 35-39; 40-44; 45-49; 50-54; and 55-59 reported as 59.5; 122.5; 188.6; 224.0; and 266.4, respectively), the likelihood of a mammogram detecting a true cancer clearly increases with age. The American Cancer Society GDG Breast Subgroup balanced the mortality reductions and population-based incidence rates against the risks of mammography “harms” (defined as needing to be recalled for additional testing via imaging and/or biopsy).

The quality of evidence for estimating risk of “overdiagnosis” (detecting a breast cancer that was not destined to be biologically significant or life threatening) was deemed to be insufficient and so this controversial metric was omitted from the final analysis. However, data regarding the general tendency for breast cancers to have more favorable biologic features (and therefore presumed to be more indolent) in older-aged women were taken into account with regard to recommendations for age-based screening intervals.

Upon review of the above incidence and mortality-related issues, the Society generated their age- and interval-based mammography screening recommendations. The recommendations were stratified as either “strong” (defined as a screening practice that “most” patients should follow, and one that could be reasonably used as a “quality criterion or performance indicator”) or “qualified” (defined as a screening practice that is reasonable for the “majority” of patients, but encouraging a balanced discussion of possible alternatives and informed decision making). The recommendations for average-risk women are summarized as follows:

• Strong Recommendation: Women should initiate screening mammography at age 45 years.

• Qualified Recommendation: Screening mammography should be performed annually between ages 45 and 54 years.

• Qualified Recommendation: Women should have the opportunity to undergo annual screening mammography between ages 40 and 44 years.

• Qualified Recommendation: Women aged 55 and older should transition to biennial screening mammography but they should have the opportunity to continue annual screening.

• Qualified Recommendation: Women should continue screening mammography until they no longer have a life expectancy of at least 10 years.

The updated American Cancer Society screening mammography guideline therefore continues to support availability of annual screening mammography for average-risk women beginning at age 40 years and continuing for as long as life expectancy supports the benefit of undergoing treatment for a screen-detected breast cancer. However, in acknowledging the increasing risk of breast cancer with age and the increased prevalence of biologically favorable breast cancers among older versus younger women, the Society stresses that screening mammography is a must by the time a woman reaches age 45, and that she can safely consider transitioning from annual to biennial screening at age 55.

Other components of the updated guideline:

While the mammography component of the breast cancer screening guidelines have provoked the most substantial discussion, they have also addressed other screening practices, and these are summarized as follows:

• Qualified Recommendation: Clinical breast examination is not recommended for breast cancer screening among average-risk women at any age.

• Not addressed in the update, and therefore not changed from prior American Cancer Society recommendation: Breast self-examination is not recommended for average-risk women at any age.

Additional issues in the screening mammography debate

While the American Cancer Society and other organizations attempt to synthesize and interpret the existing data regarding the benefits and risks of various screening practices, clinicians must also consider several public health issues when deciding upon their own screening recommendation practices:

• Disparities and variation in breast cancer patterns associated with racial/ethnic identity: Although white American women have historically had higher population-based incidence rates of breast cancer, compared with African American women, incidence rates have risen among African Americans, and 2012 data indicate comparable rates for both groups. Furthermore, breast cancer outcome disparities have worsened, with breast cancer mortality rates 42% higher for African Americans (CA Cancer J Clin. 2015 Oct 29. doi: 10.3322/caac.21320 [Epub ahead of print]). African American women have a twofold higher population-based incidence rate of the biologically more aggressive triple-negative breast cancers at all ages, and the rates among African American women in their forties is higher than those among white American women in their fifties (Cancer. 2011;117[12]:2747-53; J Natl Cancer Inst. 2015;107[6]: djv048). Prevalence of breast cancer in the premenopausal age range is also higher among African American patients. Delayed initiation of breast cancer screening, and more prolonged intervals between screenings is therefore likely to have a disproportionate impact on the breast cancer burden of the African American population.

• Demographics of the American female population: While overall population-based incidence rates of breast cancer have been stable among American women younger than age 45 years, U.S. Census data reveal 10 million more women in the 20-45 years age range for 2010, compared with 1980. The absolute number of breast cancer patients belonging to this young age category has therefore increased (JAMA Oncol. 2015;1[7]:877-8).

• Scenarios that are not relevant for routine screening recommendations: Clinicians must continue to aggressively counsel patients regarding the importance of overall breast health awareness. The development of a new breast mass, inflammatory skin changes, and/or bloody nipple discharge should prompt immediate medical attention regardless of the result and timing of the most recent mammogram. Furthermore, women facing increased risk of breast cancer because of family history, chest wall irradiation in adolescence/early adulthood, and high-risk breast biopsy pathology (atypia, lobular carcinoma in situ) are candidates for more intense surveillance such as breast MRI in addition to mammography. The most appropriate management of women with increased risk based upon mammographic density remains unclear. Lastly but extremely importantly, American-based breast cancer screening recommendations do not apply to low- and middle-income countries where screening mammography is not widely available. Clinical breast examination and breast self-examination may play a different role in the breast cancer burden of these populations.

Dr. Newman is an ACS Fellow, Director of the Breast Oncology Program, Multi-Hospital Henry Ford Health System, Detroit, and founding Medical Director, Henry Ford Health System International Center for the Study of Breast Cancer Subtypes. Dr. Newman has acted as a volunteer advisor to the American Cancer Society.

The screening mammography debate has been rekindled by the American Cancer Society’s updated guideline released in October 2015. Surgeons are now looking at yet another iteration of the optimal surveillance schedule aimed at reducing breast cancer mortality.

Nearly all breast cancer patients undergo surgery as at least one component of their care through diagnostic biopsy and/or definitive locoregional management, and many women are referred to surgeons for evaluation as well as follow-up for a variety of benign breast problems. The discussion of breast cancer screening with patients can be complicated by the many guidelines with conflicting recommendations, not to mention patient fears triggered by incompletely informed or simplistic media coverage. Surgeons are therefore obliged to remain knowledgeable regarding the status and rationale for breast cancer screening guidelines that have been developed by our colleagues in the American Cancer Society as well as other organizations.

Context of the updated guideline

The American Cancer Society and the American College of Surgeons have historically advocated in favor of annual screening mammography for average-risk women in the United States beginning at age 40 years (https://goo.gl/4W92EI). In 2009, the United States Preventive Services Task Force (USPSTF) published a recommendation that women delay initiation of screening mammography until reaching age 50, with follow-up studies performed biennially thereafter. This USPSTF guideline has remain unchanged as of 2015 (http://goo.gl/RYYWEP). Other medical societies and institutions have established their own guidelines.

The updated American Cancer Society guideline now recommends that average-risk women initiate annual mammography at age 45, but advocates in favor of availability of annual mammography beginning at age 40; the updated guideline also indicates that women can transition to biennial mammography at age 55, but should have access to continued annual mammography in accordance with personal preferences and after consideration of risks and benefits (JAMA. 2015;314[15]:1599-614).

The updated guideline can basically be interpreted as a more relaxed version of the prior guideline, which featured a straightforward mandate for average-risk women to undergo annual screening mammography beginning at age 40 years. However, the increased complexity of the more flexible guideline has generated legitimate concerns regarding the potential for confusion and misinterpretation.

Updated guideline rationale and empirical basis

The Society commissioned a systematic review to evaluate the benefits and harms of mammographic screening as well as clinical breast examination, based upon randomized clinical trials, and observational and modeling studies (JAMA. 2015;314[15]: 1615-34).

The Society then convened their Guideline Development Group (GDG) and GDG Breast Subgroup to interpret the systematic review for the purpose of drafting the breast cancer screening update. This process was further guided by a panel of External Expert Advisors. Mortality reductions were analyzed in the context of population-based breast cancer incidence rates by 5-year age increments.

Not surprisingly, the overall review confirmed the findings of several published studies that screening mammography in women aged 40-79 reduces breast cancer mortality rates by 20%-50%, with extent of benefit varying by age, as well as study design (randomized clinical trial versus observational). Since breast cancer incidence rates increase substantially among women by age (incidence rates per 100,000 population for women 35-39; 40-44; 45-49; 50-54; and 55-59 reported as 59.5; 122.5; 188.6; 224.0; and 266.4, respectively), the likelihood of a mammogram detecting a true cancer clearly increases with age. The American Cancer Society GDG Breast Subgroup balanced the mortality reductions and population-based incidence rates against the risks of mammography “harms” (defined as needing to be recalled for additional testing via imaging and/or biopsy).

The quality of evidence for estimating risk of “overdiagnosis” (detecting a breast cancer that was not destined to be biologically significant or life threatening) was deemed to be insufficient and so this controversial metric was omitted from the final analysis. However, data regarding the general tendency for breast cancers to have more favorable biologic features (and therefore presumed to be more indolent) in older-aged women were taken into account with regard to recommendations for age-based screening intervals.

Upon review of the above incidence and mortality-related issues, the Society generated their age- and interval-based mammography screening recommendations. The recommendations were stratified as either “strong” (defined as a screening practice that “most” patients should follow, and one that could be reasonably used as a “quality criterion or performance indicator”) or “qualified” (defined as a screening practice that is reasonable for the “majority” of patients, but encouraging a balanced discussion of possible alternatives and informed decision making). The recommendations for average-risk women are summarized as follows:

• Strong Recommendation: Women should initiate screening mammography at age 45 years.

• Qualified Recommendation: Screening mammography should be performed annually between ages 45 and 54 years.

• Qualified Recommendation: Women should have the opportunity to undergo annual screening mammography between ages 40 and 44 years.

• Qualified Recommendation: Women aged 55 and older should transition to biennial screening mammography but they should have the opportunity to continue annual screening.

• Qualified Recommendation: Women should continue screening mammography until they no longer have a life expectancy of at least 10 years.

The updated American Cancer Society screening mammography guideline therefore continues to support availability of annual screening mammography for average-risk women beginning at age 40 years and continuing for as long as life expectancy supports the benefit of undergoing treatment for a screen-detected breast cancer. However, in acknowledging the increasing risk of breast cancer with age and the increased prevalence of biologically favorable breast cancers among older versus younger women, the Society stresses that screening mammography is a must by the time a woman reaches age 45, and that she can safely consider transitioning from annual to biennial screening at age 55.

Other components of the updated guideline:

While the mammography component of the breast cancer screening guidelines have provoked the most substantial discussion, they have also addressed other screening practices, and these are summarized as follows:

• Qualified Recommendation: Clinical breast examination is not recommended for breast cancer screening among average-risk women at any age.

• Not addressed in the update, and therefore not changed from prior American Cancer Society recommendation: Breast self-examination is not recommended for average-risk women at any age.

Additional issues in the screening mammography debate

While the American Cancer Society and other organizations attempt to synthesize and interpret the existing data regarding the benefits and risks of various screening practices, clinicians must also consider several public health issues when deciding upon their own screening recommendation practices:

• Disparities and variation in breast cancer patterns associated with racial/ethnic identity: Although white American women have historically had higher population-based incidence rates of breast cancer, compared with African American women, incidence rates have risen among African Americans, and 2012 data indicate comparable rates for both groups. Furthermore, breast cancer outcome disparities have worsened, with breast cancer mortality rates 42% higher for African Americans (CA Cancer J Clin. 2015 Oct 29. doi: 10.3322/caac.21320 [Epub ahead of print]). African American women have a twofold higher population-based incidence rate of the biologically more aggressive triple-negative breast cancers at all ages, and the rates among African American women in their forties is higher than those among white American women in their fifties (Cancer. 2011;117[12]:2747-53; J Natl Cancer Inst. 2015;107[6]: djv048). Prevalence of breast cancer in the premenopausal age range is also higher among African American patients. Delayed initiation of breast cancer screening, and more prolonged intervals between screenings is therefore likely to have a disproportionate impact on the breast cancer burden of the African American population.

• Demographics of the American female population: While overall population-based incidence rates of breast cancer have been stable among American women younger than age 45 years, U.S. Census data reveal 10 million more women in the 20-45 years age range for 2010, compared with 1980. The absolute number of breast cancer patients belonging to this young age category has therefore increased (JAMA Oncol. 2015;1[7]:877-8).

• Scenarios that are not relevant for routine screening recommendations: Clinicians must continue to aggressively counsel patients regarding the importance of overall breast health awareness. The development of a new breast mass, inflammatory skin changes, and/or bloody nipple discharge should prompt immediate medical attention regardless of the result and timing of the most recent mammogram. Furthermore, women facing increased risk of breast cancer because of family history, chest wall irradiation in adolescence/early adulthood, and high-risk breast biopsy pathology (atypia, lobular carcinoma in situ) are candidates for more intense surveillance such as breast MRI in addition to mammography. The most appropriate management of women with increased risk based upon mammographic density remains unclear. Lastly but extremely importantly, American-based breast cancer screening recommendations do not apply to low- and middle-income countries where screening mammography is not widely available. Clinical breast examination and breast self-examination may play a different role in the breast cancer burden of these populations.

Dr. Newman is an ACS Fellow, Director of the Breast Oncology Program, Multi-Hospital Henry Ford Health System, Detroit, and founding Medical Director, Henry Ford Health System International Center for the Study of Breast Cancer Subtypes. Dr. Newman has acted as a volunteer advisor to the American Cancer Society.

The screening mammography debate has been rekindled by the American Cancer Society’s updated guideline released in October 2015. Surgeons are now looking at yet another iteration of the optimal surveillance schedule aimed at reducing breast cancer mortality.

Nearly all breast cancer patients undergo surgery as at least one component of their care through diagnostic biopsy and/or definitive locoregional management, and many women are referred to surgeons for evaluation as well as follow-up for a variety of benign breast problems. The discussion of breast cancer screening with patients can be complicated by the many guidelines with conflicting recommendations, not to mention patient fears triggered by incompletely informed or simplistic media coverage. Surgeons are therefore obliged to remain knowledgeable regarding the status and rationale for breast cancer screening guidelines that have been developed by our colleagues in the American Cancer Society as well as other organizations.

Context of the updated guideline

The American Cancer Society and the American College of Surgeons have historically advocated in favor of annual screening mammography for average-risk women in the United States beginning at age 40 years (https://goo.gl/4W92EI). In 2009, the United States Preventive Services Task Force (USPSTF) published a recommendation that women delay initiation of screening mammography until reaching age 50, with follow-up studies performed biennially thereafter. This USPSTF guideline has remain unchanged as of 2015 (http://goo.gl/RYYWEP). Other medical societies and institutions have established their own guidelines.

The updated American Cancer Society guideline now recommends that average-risk women initiate annual mammography at age 45, but advocates in favor of availability of annual mammography beginning at age 40; the updated guideline also indicates that women can transition to biennial mammography at age 55, but should have access to continued annual mammography in accordance with personal preferences and after consideration of risks and benefits (JAMA. 2015;314[15]:1599-614).

The updated guideline can basically be interpreted as a more relaxed version of the prior guideline, which featured a straightforward mandate for average-risk women to undergo annual screening mammography beginning at age 40 years. However, the increased complexity of the more flexible guideline has generated legitimate concerns regarding the potential for confusion and misinterpretation.

Updated guideline rationale and empirical basis

The Society commissioned a systematic review to evaluate the benefits and harms of mammographic screening as well as clinical breast examination, based upon randomized clinical trials, and observational and modeling studies (JAMA. 2015;314[15]: 1615-34).

The Society then convened their Guideline Development Group (GDG) and GDG Breast Subgroup to interpret the systematic review for the purpose of drafting the breast cancer screening update. This process was further guided by a panel of External Expert Advisors. Mortality reductions were analyzed in the context of population-based breast cancer incidence rates by 5-year age increments.

Not surprisingly, the overall review confirmed the findings of several published studies that screening mammography in women aged 40-79 reduces breast cancer mortality rates by 20%-50%, with extent of benefit varying by age, as well as study design (randomized clinical trial versus observational). Since breast cancer incidence rates increase substantially among women by age (incidence rates per 100,000 population for women 35-39; 40-44; 45-49; 50-54; and 55-59 reported as 59.5; 122.5; 188.6; 224.0; and 266.4, respectively), the likelihood of a mammogram detecting a true cancer clearly increases with age. The American Cancer Society GDG Breast Subgroup balanced the mortality reductions and population-based incidence rates against the risks of mammography “harms” (defined as needing to be recalled for additional testing via imaging and/or biopsy).

The quality of evidence for estimating risk of “overdiagnosis” (detecting a breast cancer that was not destined to be biologically significant or life threatening) was deemed to be insufficient and so this controversial metric was omitted from the final analysis. However, data regarding the general tendency for breast cancers to have more favorable biologic features (and therefore presumed to be more indolent) in older-aged women were taken into account with regard to recommendations for age-based screening intervals.

Upon review of the above incidence and mortality-related issues, the Society generated their age- and interval-based mammography screening recommendations. The recommendations were stratified as either “strong” (defined as a screening practice that “most” patients should follow, and one that could be reasonably used as a “quality criterion or performance indicator”) or “qualified” (defined as a screening practice that is reasonable for the “majority” of patients, but encouraging a balanced discussion of possible alternatives and informed decision making). The recommendations for average-risk women are summarized as follows:

• Strong Recommendation: Women should initiate screening mammography at age 45 years.

• Qualified Recommendation: Screening mammography should be performed annually between ages 45 and 54 years.

• Qualified Recommendation: Women should have the opportunity to undergo annual screening mammography between ages 40 and 44 years.

• Qualified Recommendation: Women aged 55 and older should transition to biennial screening mammography but they should have the opportunity to continue annual screening.

• Qualified Recommendation: Women should continue screening mammography until they no longer have a life expectancy of at least 10 years.

The updated American Cancer Society screening mammography guideline therefore continues to support availability of annual screening mammography for average-risk women beginning at age 40 years and continuing for as long as life expectancy supports the benefit of undergoing treatment for a screen-detected breast cancer. However, in acknowledging the increasing risk of breast cancer with age and the increased prevalence of biologically favorable breast cancers among older versus younger women, the Society stresses that screening mammography is a must by the time a woman reaches age 45, and that she can safely consider transitioning from annual to biennial screening at age 55.

Other components of the updated guideline:

While the mammography component of the breast cancer screening guidelines have provoked the most substantial discussion, they have also addressed other screening practices, and these are summarized as follows:

• Qualified Recommendation: Clinical breast examination is not recommended for breast cancer screening among average-risk women at any age.

• Not addressed in the update, and therefore not changed from prior American Cancer Society recommendation: Breast self-examination is not recommended for average-risk women at any age.

Additional issues in the screening mammography debate

While the American Cancer Society and other organizations attempt to synthesize and interpret the existing data regarding the benefits and risks of various screening practices, clinicians must also consider several public health issues when deciding upon their own screening recommendation practices:

• Disparities and variation in breast cancer patterns associated with racial/ethnic identity: Although white American women have historically had higher population-based incidence rates of breast cancer, compared with African American women, incidence rates have risen among African Americans, and 2012 data indicate comparable rates for both groups. Furthermore, breast cancer outcome disparities have worsened, with breast cancer mortality rates 42% higher for African Americans (CA Cancer J Clin. 2015 Oct 29. doi: 10.3322/caac.21320 [Epub ahead of print]). African American women have a twofold higher population-based incidence rate of the biologically more aggressive triple-negative breast cancers at all ages, and the rates among African American women in their forties is higher than those among white American women in their fifties (Cancer. 2011;117[12]:2747-53; J Natl Cancer Inst. 2015;107[6]: djv048). Prevalence of breast cancer in the premenopausal age range is also higher among African American patients. Delayed initiation of breast cancer screening, and more prolonged intervals between screenings is therefore likely to have a disproportionate impact on the breast cancer burden of the African American population.

• Demographics of the American female population: While overall population-based incidence rates of breast cancer have been stable among American women younger than age 45 years, U.S. Census data reveal 10 million more women in the 20-45 years age range for 2010, compared with 1980. The absolute number of breast cancer patients belonging to this young age category has therefore increased (JAMA Oncol. 2015;1[7]:877-8).

• Scenarios that are not relevant for routine screening recommendations: Clinicians must continue to aggressively counsel patients regarding the importance of overall breast health awareness. The development of a new breast mass, inflammatory skin changes, and/or bloody nipple discharge should prompt immediate medical attention regardless of the result and timing of the most recent mammogram. Furthermore, women facing increased risk of breast cancer because of family history, chest wall irradiation in adolescence/early adulthood, and high-risk breast biopsy pathology (atypia, lobular carcinoma in situ) are candidates for more intense surveillance such as breast MRI in addition to mammography. The most appropriate management of women with increased risk based upon mammographic density remains unclear. Lastly but extremely importantly, American-based breast cancer screening recommendations do not apply to low- and middle-income countries where screening mammography is not widely available. Clinical breast examination and breast self-examination may play a different role in the breast cancer burden of these populations.

Dr. Newman is an ACS Fellow, Director of the Breast Oncology Program, Multi-Hospital Henry Ford Health System, Detroit, and founding Medical Director, Henry Ford Health System International Center for the Study of Breast Cancer Subtypes. Dr. Newman has acted as a volunteer advisor to the American Cancer Society.