Mammography Debate: To Screen, Or Not To Screen?

In a much-tweeted cover story for the New York Times Magazine, Peggy Orenstein wrote that she once believed a mammogram saved her life. Sixteen years later, after dealing with breast cancer round two, she says she now wonders whether that first mammogram mattered at all. “Would the outcome have been the same,” she writes in Our Feel-Good War on Breast Cancer, “had I bumped into the cancer on my own years later?”

111018012923-mammogram-breast-cancer-x-ray-story-topResearchers have asked this same question for many years. Following hundreds of thousands of women over long periods of time, randomized clinical trials have found that very few women have their lives saved by routine mammogram screenings. Instead, women who have regular screenings are more likely to experience unnecessary treatment (such as biopsies, surgeries, and drugs for benign conditions or risk factors that were not themselves life-threatening). A leading source of health-care analysis, the Cochrane Collaboration, analyzed clinical studies and found that “for every 2,000 women invited for screening throughout 10 years, one will have her life prolonged,” and “10 healthy women … will be treated unnecessarily.”

Unless we have high odds for winning the lottery, probabilities are not something most of us want to hear. We’ve been told for years that finding breast cancer “early” increases a person’s chances of not dying from the disease, and that mammograms are the gold standard for finding breast cancer early.

The problem screening mammography is that some breast cancers don’t show up well on mammograms, or at all; some cancers, even though they may be small, have already spread throughout the body; and some of the most aggressive types of breast cancer show up between mammograms. In the end, “early” may not be early enough in determining prognosis. Researchers have identified at least ten molecular types of breast cancer, each associated with different prognoses. Because of cancer’s complexity, the limitations of x-rays and computer-aided technologies, as well as differences in expertise among radiologists and diagnostic centers, screening has helped to reduce the relative disease-specific death rate by only about 15 percent. Some studies put the screening-associated reduction as low as zero. And to date, very large studies have failed to find reductions in all-cause mortality for mammography screening for any age group.

A typical response to concerns over the limitations and risks of routine screening is to observe that “mammograms are not perfect.” In reality, costly programs of regular screening result in under-diagnosing some people and over-diagnosing others — as much as 30 percent of women who get regular mammograms experience over-diagnosis and the treatments that go along with it. The net effect: Fewer lives are being saved than anticipated and more people harmed. With such high rates of over-diagnosis and over-treatment, questions are growing about just who really ought to be screened, and how often.

There is no doubt about the importance of mammograms as a diagnostic tool — that is, as a test for women who have symptoms of a problem. But there is mounting support for the 2009 United States Preventive Services Task Force recommendation of fewer screenings for most women (every other year from age 50 to 75). In the midst of shifting protocols, what is a woman of average risk to do?

Well, here is what I do. I remind myself that screening mammography is an option with risks, not an imperative. I look for balanced information about the benefits and harms of routine screening. I avoid health messages on pink products. I ask my doctor, “What do you think you will learn from that test, and what will we do with the information?” And I urge researchers and other experts in the public health sector to take women’s concerns seriously, to acknowledge the harms associated with screening, and instead of just telling us what to do, to take steps to address these issues so we’re not having still this conversation in another 30 years. Rather than spending billions on advertising campaigns to convince women to “just do it” and get mammograms, I’d rather see those funds go to treatments against the most deadly metastatic breast cancer and efforts to stop the disease before it starts.

Originally Published by Gayle Sulik,, May 20, 2013.

TIP: The Harding Center for Risk Literacy prepared a facts box with neutral and easy-to-understand information about the harms and benefits of routine population-based screening. The numbers refer to 2,000 women over 50 years of age who participated in screening for 10 years (screening group), compared to 2,000 women of the same age who did not participate in the screening during the same period (control group).


The box shows that mammography screening reduced the number of breast cancer deaths from 8 to 7 in 2,000 women. This effect had no influence on all-cancer mortality: the number of women who died of any cancer was the same in both groups. However, 200 of 2,000 women in the screening group had at least one suspicious screening result within the 10 years that later proved to be a false alarm.

Mammography screening also detects “indolent” (slowly growing or less aggressive) tumors, which would never develop into a life-threatening disease. Because their development cannot be predicted about 10 of 2,000 women in the screening group had their breast completely or partially removed.


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