The Breast Cancer Screening Debate
Screening mammography has been the subject of recent intense debate, largely fueled by conflicting national guidelines and varying interpretations of the studies examining the effectiveness of breast cancer screening. Controversy arises over when to start screening mammography, how often to have a mammogram, and at what age woman should stop getting mammograms.
Although treating breast cancer at an earlier stage is associated with a better likelihood of survival, questions arise due to concerns of over-diagnosis and over-treatment (i.e., finding and treating small, indolent breast cancers that would never have caused any harm if left alone). Both patients and health care professionals alike have been left somewhat in the dark as to the best approach of taking advantage of early detection while minimizing the risk and harms of over-diagnosis of breast cancer. New recommendations from the American Cancer Society (ACS) have emerged and aim to shed light on the situation.
Breast cancer remains an all too prevalent disease, affecting women worldwide. Estimates in the United States alone report that 231,840 new cases of invasive breast cancer and 60,290 new cases of ductal carcinoma in situ (an early, non-invasive form of breast cancer) will be diagnosed in women in 2015. It is widely recognized that early detection of breast cancer saves lives and that screening mammography is the most effective means of early detection. In fact, mortality from breast cancer has been decreasing steadily since 1990, due to improvements in early detection and advances in treatment. However, screening mammography has become a double-edged sword as breast abnormalities can now be identified at such an early form that their potential to cause harm is unknown. Treatment may or may not be necessary for some of these early cancers.
For several decades, the ACS has published evidence-based guidelines on cancer screening for many common cancer types. Previously, their guideline recommended yearly mammograms starting at age 40 and continuing for as long as a woman is in good health. They also recommended clinical breast exam (a physical exam of the breast performed by a health professional) every year for women 40 and over. These recommendations conflicted with those of the United States Preventive Services task Force (USPSTF) guideline, which recommends screening mammography for women between age 50 and 74, with the frequency of mammograms being every other year. The USPSTF is an independent, volunteer panel of national experts in prevention and evidence-based medicine. The USPSTF also concludes that “the current evidence is insufficient to assess the additional benefits and harms of clinical breast examination beyond screening mammography in women 40 years or older” and that “the current evidence is insufficient to assess the benefits and harms of screening mammography in women 75 years and older.” Both the ACS and USPSTF are frequently referred to when setting clinical practice standards, public health policy and health care legislation. The stark differences in recommendations between these two national guidelines have served as a source of contention and confusion.
On October 20, 2015 the ACS released a new guideline for screening mammography, published in the Journal of the American Medical Association. The recommendations were derived from a voluntary panel of experts convened by the American Cancer Society, – the Guideline Development Group (GDG) – who commissioned an independent review of available evidence from published medical studies on breast cancer screening.
Overview of the ACS Recommendation
The new guideline from the ACS recommends that women at average risk for breast cancer should begin annual mammography at age 45. This is a significant departure from earlier recommendations supporting that screening start at age 40. According to the ACS, “while mammography is beneficial beginning at age 40, the balance of its potential to reduce death from breast cancer to the harms associated with false positive imaging tests, biopsies, and over-diagnosis becomes more favorable at age 45.” The ACS guideline also recommends that average risk women at age 55 should transition to screening every two years. This is also a departure from previous ACS recommendations, which supported annual screening in this older age group. The ACS states that the reason for these changes is due to the considerable amount of new data that has emerged since their last review of the literature in 2003.
Despite these changes, the ACS guideline asserts that women should still have the opportunity to begin screening as early as age 40, and to continue screening every year at age 55 depending on their personal values and preferences. The ACS states: “because some women will regard the greater odds of experiencing a false positive test as a reasonable trade-off for the potential benefit, all women should have the opportunity to begin annual screening between the ages of 40 and 44. Women should also have the option to continue screening every year after age 55, again based on her health, personal values, and preferences.”
Of particular interest, clinical breast examination (CBE) is no longer recommend at any age as part of breast cancer screening among asymptomatic women with an average risk of breast cancer. This does not mean that clinical breast exams should not be performed if a woman has symptoms (e.g., a breast lump or pain). Women with breast complaints still require a clinical breast exam as part of the assessment of that complaint or problem. Also, women at high risk (e.g., prior breast cancer, strong family history, a known genetic predisposition to breast cancer) may still benefit from regular clinical breast exams performed by a health care professional. The ACS anticipates a separate set of recommendations for high-risk woman, including the role of CBE, to be published in 2016.
Summary of 2015 changes
- The ACS recommends that women at average risk start annual screening with mammography at age 45, and that women age 40 to 44 should have the opportunity to start screening early if they choose. (Previously the ACS had recommended that women at average risk start annual screening with mammography at age 40).
- The ACS recommends that women should transition to screening every two years starting at age 55, but can also choose to continue screening annually. (Previously the ACS had recommended that women continue screening for as long as they remained in good health).
- The ACS no longer recommends clinical breast exam (CBE) as a screening method for women in the United States.
ACS statement excerpt “The risk of cancer is lower for women ages 40-44 and the risk of harms associated with false positive findings (biopsies, over-diagnosis) is somewhat higher, and that the balance becomes more favorable at age 45; thus, a direct recommendation to begin screening at age 40 was no longer warranted. However, because the evidence supports that there is some benefit from screening with mammography for women between 40 and 44, the ACS concluded that women in this age group should have the opportunity to begin screening based on their preferences and their consideration of the tradeoffs.”
- Begin screening at age 45 every year
- Transition to every other year at age 55
- Screening should be every two years
- Begin screening at age 50
*Both the American Cancer Society and USPSTF recommend that starting at age 40, women have the opportunity to begin screening based on a woman’s values, preferences, and health history.
My Initial Two Cents
As a surgical oncologist actively involved in the management of patients with breast disease, early detection of cancer is of paramount importance in achieving optimal outcomes for my patients. The fundamental challenge of population-based screening is to maximize lifesaving benefits of screening while minimizing harms. While I appreciate the flexibility and individualized components of the new recommendations, I remain concerned for women aged 40-44 who may harbor active disease that would only be identified with screening. With that said, the updated ACS guideline on screening appears to be an attempt to balance the risks and benefits of screening mammography.
There is greater consensus between the ACS and USPSTF guidelines, and this may help to reduce confusion about treatment recommendations. However, there is still an issue with women age 45-55, as both guidelines differ on recommendations for this age group. I also have no doubt that there will be many in-depth discussions about individual options for woman age 40-44, who are not recommended, but have the option for screening according to the new ACS guideline. I believe that the overall discourse will be valuable for promoting shared decision-making and care that is focused on each patient’s individual values, personal preferences, and unique risk profiles.
It is important not to erroneously interpret the new ACS guideline recommendations to suggest that there is no benefit to age-appropriate screening or in the timely clinical assessment of a breast complaint. The ACS guideline affirms that women still benefit from screening mammograms, at the applicable age and frequency outlined. Also, the ACS guideline is for average risk women, and may not be well-suited to higher risk populations such as the patients frequently encountered at the UVM Breast Care Center.
Another consideration is that breast cancer, when identified at a later stage, may often require more extensive treatment (e.g., mastectomy, chemotherapy) in comparison to earlier stage cancers identified on mammogram. Although there may be no difference in overall survival, the more extensive treatments could result in greater functional limitations, higher risk of complications, extended recovery periods and other increased personal costs. It remains completely unknown whether or not the new ACS guideline recommendations will actually result in breast cancers being larger or more extensive at the time of diagnosis.
One can also speculate what the impact may be on insurance coverage for mammograms and on financial support programs that fund breast cancer screening. Despite the fact the ACS guideline leaves the option for screening open to women starting at the age of 40, federal and private programs may not support this decision financially given the formal recommendation of screening at age 45. Only time will tell.
Finally, it is important to recognize that perhaps an even greater issue in the management of breast cancer is access to care. There remain persistent barriers to timely preventive services especially among lower resource patient populations. Efforts need to be maintained to ensure that all women have access to age-appropriate and risk-appropriate breast cancer screening and subsequent treatment as needed.
Take Home Points
- The new ACS guideline supports the use of screening mammography as the most effective way for a woman to reduce her likelihood of dying from breast cancer. However, changes have been made to the age and frequency of screening recommendations.
- The ACS guideline attempts to minimize the harms of over diagnosis including unnecessary additional procedures.
- The ACS recommendations are for women with average breast cancer risk. Women at high risk (e.g. strong family history, genetic factors/BRCA), would not meet criteria for this guideline and may need to begin screening earlier and more frequently.
- The ACS recommendations offer a more customized approach to breast cancer screening based on a woman’s individual risk, personal values and preferences.
Ted A. James, MD, MS, FACS is a professor of surgery and Director of Skin and Soft Tissue Surgical Oncology at the University of Vermont. He is a member of the UVM Cancer Center. He is the Vermont State Chair for the Commission on Cancer and serves on the Board of Directors for the New England division of the American Cancer Society.