As a gynecologist and a breast cancer survivor, I am acutely aware of the controversy and questions surrounding mammograms.
Different organizations have different guidelines. The US Preventative Task Force or USPTF ruffled a few feathers in 2009 when they came out with new guidelines recommending routine screening mammography start at age 50 and continue biennially until age 74. The USPTF states there is not enough data to recommend routine, screening mammography to all women age 40-49. Instead, it should be a personal decision. These guidelines, which were updated in 2015, continue to recommend biennial screening starting at age 50 and have largely been ignored.
The American Cancer Society also updated their recommendations in 2015 and now recommend personalized decisions from age 40-44, routine annual screening from age 45-55 and biennial screenings after that.
The American Congress of Obstetricians and Gynecologists recommend annual screening starting at age 40.
The results of a recent survey published this month in JAMA indicates what happens in clinical practice, which has changed very little since 2009 with 81% of physicians recommending screening for women ages 40-44 and 88% recommending it for women ages 45-49.
Drs Deborah Grady and Rita Redberg in an editorial also in JAMA state, “In our view the most evidenced-based, transparent, conflict-free guidelines are from the USPTF.” They go on to say, “physicians inexplicably trusted guidelines other than the USPTF which is publicly funded, uses strict methods and carefully supports recommendations with evidence.”
So why aren’t women and their physicians following these evidence-based guidelines?
One likely reason women and their doctors continue to get and recommend annual mammograms starting at age 40 is the theory that early detection saves lives. But unfortunately, this may be just a theory.
Peggy Ornstein writes in the NYT magazine in 2013 about her experience with breast cancer. She was diagnosed with breast cancer at age 35 after obtaining the then recommended baseline mammogram before age 40. For years after her diagnosis, she thought she was saved by that mammogram. But, as she says, “study after study revealed the limits of screening — and the dangers of overtreatment — a thought niggled at my consciousness. How much had my mammogram really mattered?” She realized maybe she would have done just as well if, several years later, she detected it on her own. Of course, she will never know.
Best-selling author and general surgeon Dr. Atul Gawande writes about the avalanche of unnecessary medical care in a May 2015 edition of the New Yorker. “We’ve long assumed that if we screen a healthy population for diseases like cancer or coronary artery disease, and catch those diseases early, we’ll be able to treat them before they get dangerously advanced, and save lives in large numbers. But it hasn’t turned out that way.”
Screening mammography has significantly increased the number of women being diagnosed and treated for breast cancer, yet the number of deaths has decreased only slightly if at all.
Gawande quotes Dr. H. Gilbert Welch, a Dartmouth Medical School professor, when saying, “cancers are all like rabbits that you want to catch before they escape the barnyard pen. But some are more like birds—the most aggressive cancers have already taken flight before you can discover them, which is why some people still die from cancer, despite early detection. And lots are more like turtles. They aren’t going anywhere. Removing them won’t make any difference.” Gawande suggests that both prostate and breast cancer are usually turtles.
Dr. Welch has written extensively about the problems created by overtesting, overdiagnosing and overtreating cancer. Welch and co-author Dr. Archie Bleyer published their research examining 30 years of mammography on the stage-specific incidence of breast cancer in the NEJM in October 2012. This research shows an explosion of early stage disease concurrent with the widespread use of mammography but only a tiny decrease in the incidence of late-stage disease. Detecting many more breast cancers at an early stage has only prevented a very small number of women from presenting with late stage disease. This imbalance indicates overdiagnosis, estimated by this data to be over a million women in the past 30 years, and 70,000 in 2008 alone, which ends up being approximately 31% of all breast cancers diagnosed in women over 40.
Despite the potential harms of overdiagnosis, the USPTF concludes the benefits of mammography in women ages 50-74 outweigh the risks. For women in their 40s, the risks are greater, and the benefit is smaller than for women 50 and older. Both because the incidence of breast cancer is less, and mammography is less accurate in this age range. It still may save lives but for a much higher price with many more women being overdiagnosed and treated.
Women are at risk of developing breast cancer. This level of risk steadily increases with age. The decision to start and how often to obtain a mammogram should be an individual one. Women should be carefully counseled on the limitations of mammography, and those with higher risks and greater distress may choose to start screening earlier than women whose concerns are more about overdiagnosis and overtreatment.