Who to Believe: Making Sense of Breast Cancer Screening Guidelines
By Nicole Choy
In April of 2019, the American College of Physicians (ACP) released new guidance statements for mammogram screenings for average-risk women. The ACP regularly releases guidance statements generated for topics where numerous existing guidelines conflict; and when it comes to mammograms, there is a good amount of confusion. Most guidelines are supported by research, and the reason for the discrepancies can be traced to different findings measuring the effectiveness of screening depending on when women start screening, how often they receive it, and when it would be appropriate to stop screening–if at all. Furthermore, different guidelines are targeted to different populations of patients such as women at an average or population risk for breast cancer or women with a higher risk associated with one or multiple factors. Overall, the discrepancies between guidelines can confuse patients as to which is the best practice to follow when it comes to mammogram screenings.
The ACP guidance statements were formulated based on an in-depth analysis of several breast cancer screening guidelines from the American College of Radiology (ACR), American Cancer Society (ACS), the U.S. Preventive Services Task Force (USPSTF), the World Health Organization (WHO), the Canadian Task Force on Preventive Health Care (CTFPHC), National Comprehensive Cancer Network (NCCN), and the American College of Obstetricians and Gynecologists (ACOG). This included a review of all of the supporting evidence associated with those guidelines, as well as a review of each of the guidelines by several authors, and based on the amount of evidence and degree to which the evidence was consistent with one another, the ACP generated five guidance statements.
Guidance Statement 1: In average-risk women aged 40 to 49 years, clinicians should discuss whether to screen for breast cancer with mammography before age 50 years. Discussion should include the potential benefits and harms and a woman’s preferences. The potential harms outweigh the benefits in most women aged 40 to 49 years.
Guidance Statement 2: In average-risk women aged 50 to 74 years, clinicians should offer screening for breast cancer with biennial mammography.
Guidance Statement 3: In average-risk women aged 75 years or older or in women with a life expectancy of 10 years or less, clinicians should discontinue screening for breast cancer.
Guidance Statement 4: In average-risk women of all ages, clinicians should not use clinical breast examination to screen for breast cancer.
Who is at an average-risk for breast cancer?
The ACP defines women to be of average-risk if they have no personal history of breast cancer or history of any high-risk breast lesions, are not known to carry a genetic mutation known to be associated with an increased risk of breast cancer (for example BRCA 1/2), and did not have any radiation exposure to their chest in childhood. While some guidelines define average-risk differently, and some women may be at an increased risk for breast cancer due to other factors (including but not limited to factors such as hormone therapy or breast density), the ACP guidelines are considered to be inclusive of all women of average-risk.
The majority of the guidelines agreed that the best time to start discussing when to start screening was at 40 years of age; and most guidelines agreed that mammogram screenings for average-risk women were appropriate between the ages of 50 and 74 years. However, the ACP found that guidelines conflicted regarding whether screening was appropriate for women outside of that age range. It appears most of the supporting evidence used to formulate the various guidelines disagree when it comes to the ages at which mammograms would be the most beneficial in preventing breast cancer associated deaths. All of the guidelines agreed that mammograms were most effective in preventing breast cancer associated deaths in women age 50 to 69. However, only a couple of guidelines had evidence to suggest that mammogram screening for women between the ages of 39 and 49 outweighed the risks of early mammogram screening. Furthermore, as women get older, their remaining lifetime risk for breast cancer goes down.
However, there has been some controversy regarding the ACP’s guidance statements. Following the publication, the American College of Radiology (ACR), one of the organizations that was included in their review of guidelines, came out with a statement opposing the guidance statements, stating that, “Screening only women ages 50-74 every other year, as now recommended by the American College of Physicians (ACP) and the US Preventive Services Task Force, may result in up to 10,000 additional, and unnecessary, breast cancer deaths in the United States each year.” The ACR goes on to address several claims made by the ACP in their report that are inaccurate, and suggests that the ACP guidelines neglect to include factors such as racial disparities into their guidance statements. Finally, the ACR concludes by explaining that the guidance statements greatly underestimate the benefits of annual mammograms and overstate the risks of harm.
So which guidelines should we follow?
Guidelines are useful in helping doctors to determine the best schedule for screening for their patients, but they are in no way a hard and fast rule that doctors are required to follow. In 2017, a study was published that presented data on what screening guidelines doctors recommended and which guidelines they trusted the most. The majority of doctors recommended some form of screening for women starting at the age of 40, with the majority recommending annual mammograms. However, in a BreastCancer.Org article discussing the study, Craig Pollack, associate professor of medicine at Johns Hopkins and co-author of the aforementioned study, stated, “Doctors need to work with patients to help them come to breast cancer screening decisions that are right for them.”
Ultimately, the best option for individuals who receive mammograms, is to speak with their doctors to go over what screening schedule is best for them. After all, many of these guidelines are only applicable to a certain population, such as average-risk individuals, and in reality people rarely fit into a neat little boxes of population demographics.
How do you know if you’re at an increased risk?
There are several factors that increase an individual’s risk for breast cancer; age, being a woman, and having a personal or family history of breast cancer can shift an individual to have an above average risk. Other factors, such as genetic mutations like BRCA1/2, ATM, CHEK2, and TP53 (just to name a few) can also contribute to an increased risk. It is important to talk to your doctor if you think you might be at an increased risk for breast cancer. If you doctor hasn’t discussed your personal or family history of cancer, it may be your responsibility as a patient to bring it up. If you don’t feel comfortable, seeking a second opinion or speaking directly with a genetic counselor can also be a great way of learning more about your personal risks for breast cancer.
Not sure where to find a genetic counselor?
Grey Genetics has a network of qualified genetic counselors who are well-equipped to provide cancer genetic counseling. If you aren’t sure if you’re ready to speak with a genetic counselor, but still want to learn more about how your family medical history could impact your cancer risks, Grey Genetics also offers family history review services. Regardless of what you may want to know about your individual risk for breast cancer, we offer a few options that are the best fit for you and your budget.
Further Reading & Quality News Coverage
Qaseem, A.; Lin, J.S.; Mustafa, R.A.; Horwitch, C.A.; Wilt, T.J.. “Screening for Breast Cancer in Average-Risk Women: A Guidance Statement From the American College of Physicians.” Annals of Internal Medicine. 16 April 2019.
Monticciolo, D.; Newell, M.; Hendrick, R.E.; Helvie, M.; et al. “Breast Cancer Screening for Average-Risk Women: Recommendations From the ACR Commission on Breast Imaging.” Journal of the American College of Radiology. January 2018.
Oeffinger, K.; Fontham, E.; Etzioni, R.; et al. “Breast Cancer Screening for Women at Average Risk 2015 Guideline Update From the American Cancer Society.” JAMA. 20 October 2015.
“Breast Cancer: Screening.” US Preventive Services Task Force. Published: November 2009. Updated: May 2019.
“WHO Position Paper on Mammography Screening.” World Health Organization. 2014.
“Breast Cancer Update (2018).” Canadian Task Force on Preventive Health Care. 10 December 2018.
Bevers, T.; Helvie, M.; Bonaccio, E.; Calhoun, K.; Daly, M.; Farrar, W; et al. “Breast Cancer Screening and Diagnosis, Version 3.2018, NCCN Clinical Practice Guidelines in Oncology.” Journal of National Comprehensive Cancer Network. November 2018.