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Slow progress in reducing breast cancer overscreening

American women are still getting too many mammograms. Despite recommendations from the US Preventive Services Task Force and the American Cancer Society against routine screening for breast cancer before age 50, the rates of mammogram screening have not changed significantly in the past ten years.

In a recent JAMA Clinical Update, Dr. Nancy Keating and Dr. Lydia Pace from the Brigham and Women’s Hospital in Boston suggest that a key barrier to reducing unnecessary mammograms is the lack of real shared decision making.

Source: Keating NL, Pace LE. Breast Cancer Screening in 2018Time for Shared Decision Making. JAMA. 2018;319(17):1814–1815. doi:10.1001/jama.2018.3388

For a woman in her 40s, mammograms have a much greater possibility of harm than they do benefit; for every 10,000 women in their 40s who are screened, three fewer will die of breast cancer in ten years, but 6,130 will have a false positive test, 700 will receive an unnecessary biopsy, and there will be no reduction in all-cause mortality. However, the benefit of potentially not dying from breast cancer, however small, is worth the greater risk of stress from a false positive or pain of a biopsy for some women. That’s why the USPSTF and ACS recommend that the decision about whether or not to have a mammogram should be based on a woman’s specific preferences and values, as well as their individual risk factors.

However, engaging in conversations with patients about the risks and benefits of mammograms is easier said than done. Messaging that touts the benefits of mammograms is ubiquitous, while information on the potential harms is scarce. The American College of Radiology sponsors a website called “Mammography Saves Lives.” Some hospitals encourage women age 40 and above to schedule an annual mammogram because “it might save your life.” 

When the UK National Health Service had a computer glitch that failed to remind 450,000 older women to get a mammogram, newspapers reported that “270 women may have died” because they missed their screening. As Kevin Lomangino writes in Health News Review, these scary headlines miss the fact that breast cancer screening does not save lives when you look at all-cause mortality, rather than just deaths from breast cancer. This could be because harms from aggressive treatments after screening cancel out the benefits of fewer cancer deaths. The news coverage of the NHS story also missed opportunities to talk about the potential harms of overdiagnosis and overtreatment from mammograms. 

“The point is not that mammograms are useless and should be avoided — it’s that the benefits are probably smaller than most women have been led to believe,” writes Lomangino. “News coverage of mammograms doesn’t help when it reinforces misconceptions about the effectiveness of screening and doesn’t address the harms.”

With plenty of misinformation about mammograms and limited time at the doctor’s office, how can clinicians facilitate informed, shared decision-making conversations? Decision aids like infographics and theaters have been helpful in making the risks and benefits of mammograms more clear.

Lown 2018 speaker and family medicine physician Dr. Ronald Adler recently published a series of decision aids designed to engage patients in discussions about cancer screening. Cancer Screening Decision: A Patient-Centered Approach uses a visual, step-by-step approach for making decisions around breast cancer screening, as well as several other common cancers. 

At the same time, we also have to get better at talking about what the harms of overdiagnosis and overtreatment really mean for patients. Patients may know that they have a certain chance of getting a biopsy or false positive from a mammogram, but unless they know someone who has experienced it, they might not know what these procedures actually feel like, physically and mentally. Just as we have many stories of breast cancer survivors who can speak to that lived experience, we need to engage with more people who have experienced overdiagnosis and can talk about what it feels like.  

We’re going to need a multi-pronged approach, engaging clinicians, patients, and the media, to reduce unnecessary breast cancer screening.