The power of gut feeling in cancer screening

Cancer screening has always been an emotional topic.

In recent years, both prostate and breast cancer screening have come under increasing scrutiny. Studies are beginning to question the benefits of early detection, and, in the case of prostate cancer screening, whether more harm is done than good.

In fact, the USPSTF recently downgraded their prostate cancer screening recommendation.

In a recent study from the Archives of Internal Medicine, researchers conclude that the benefits of breast cancer screening are overstated:

Among the 60 percent of women with breast cancer who detected the disease by screening, only about 3 percent to 13 percent of them were actually helped by the test, the analysis concluded.

Translated into real numbers, that means screening mammography helps 4,000 to 18,000 women each year. Although those numbers are not inconsequential, they represent just a small portion of the 230,000 women given a breast cancer diagnosis each year, and a fraction of the 39 million women who undergo mammograms each year in the United States.

The increasingly nuanced view of cancer screening is going to take a significant communications commitment to convince patients, who tend to prefer black and white options.

How can statistics compete with the patient anecdote? Saying that a “screening mammogram helps [only] 4,000 to 18,000 women each year” will not persuade someone who knows a friend whose life was saved by a mammogram.

Consider this typical patient response, courtesy of the New York Times’ Well blog:

I have heard this before and wish I could understand it. I just can’t square the math with my gut feeling and I wonder if other women feel the same. I know 3 people who have had breast cancer, one detected by screening, two by palpitation. The one who found hers by screening is alive the other two are not. One found hers before it moved through her body, the other two did not.

I certainly don’t want to have unnecessary tests, but it seems clear (at least to my gut) that earlier detection might have reached my two friends before their cancers became unmanageable.

I applaud Dr. Gilbert Welch and the Dartmouth researchers for their continuing effort to cast evidence-based doubt on cancer screening and publicize the real threats of overtesting.

But their job is only half-done. To convince patients they need to better utilize the power of story to overcome conventional gut feeling.

 is an internal medicine physician and on the Board of Contributors at USA Today.  He is founder and editor of, also on FacebookTwitterGoogle+, and LinkedIn.

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