Lessons from the Mammography Wars

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A thoughtful piece was published in the New England Journal of Medicine about the miscommunication that took place last November of what the USPSTF tried to convey and the complicity of certain organizations in adding to that confusion.

http://healthpolicyandreform.nejm.org/?p=12525

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Dr. Peter C. Gotzsche of the Nordic Cochrane Center in Copenhagen, a nonprofit group that reviews health care research, has said in response to the just released study out of Sweden is that the investigators counted the number of women who received a diagnosis of breast cancer and also died of it. They did not compare the broader breast cancer death rates in the counties.

He said it is an important distinction because screening finds many cancers that do not need to be treated or found early. With more harmless cancers being found in the screened group, it will look like the chance of surviving breast cancer is greater in that group. "The analysis is flawed," he said.

And Donald Berry, a statistician at MD Anderson Cancer Center, responded that the overdiagnosis problem was a serious one. "We are finding cancers that would never be found if we didn't look," he was quoted for the media. "Small wonder people think screening is great - some of the cancers it finds were not lethal in the first place."

It seems like the new Swedish study (not a randomized trial) would be far from convincing and probably wouldn't meet the USPSTF test for high-grade evidence. The authors made no adjustment for any risk factors.

The absolute risk revealed was quite small, about two-tenths of one percent. There were a total of 1,824 breast cancer deaths in the entire cohort, or roughly one of every 550 women. According to the authors of the study, 1,250 women in their 40's would have to be routinely given mammograms to prevent one breast cancer death.

As a result, a much larger proportion of those women would get false cancer signals, leading to unnecessary biopsies and other treatments. It was even suggested by the American Society of Clinical Oncology (ASCO) that women under 50 discuss with their doctors their own situation and the risks and benefits before going forward with routine mammograms.