New York Times Explores How Task Force Reached Controversial Mammogram Recommendations

Main Category: Breast Cancer
Also Included In: Women's Health / Gynecology
Article Date: 25 Nov 2009 - 3:00 PDT

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The New York Times on Monday examined the U.S. Preventive Services Task Force's process for developing its recent recommendation that most women begin biennial mammograms at age 50, rather than annual screenings beginning at age 40.

According to the Times, the HHS-appointed, 16- member task force initially thought it would be performing "a straightforward job" a few years ago when it set out to examine the latest science about the benefits and risks of breast cancer screening, when to begin mammography and the optimal frequency of the screenings. The task force members did not anticipate the "swift and angry" response from many professional organizations, advocacy groups and politicians who claimed the guidelines would discourage a lifesaving test, the Times reports. Some politicians charged that the changes were politically motivated.

First, the group obtained a review of breast cancer screening studies from researchers at Oregon Health and Science University, which had done a similar review for the panel for its 2002 breast cancer screening guidelines. The university presented the task force with a large study from England that found no statistically significant decline in the 10-year breast cancer death rate for women who began screenings at age 40. Other studies showed similar results. After combining results from several analyses, the task force concluded that mammograms provide a 15% decline in the death rate from breast cancer for women in their 40s, meaning that 1,900 women ages 40 through 50 would have to be screened to prevent a single breast cancer death over as many as 20 years.

To assess harms from screening, the group studied data from the National Cancer Institute showing that women who had mammograms in their 40s had a 10% chance of getting a false positive and a 1% chance of undergoing a biopsy each time they have the screening. These data suggested a high rate of overdiagnosis, subjecting women to "chemotherapy, radiation and surgery for tumors that do not need treating," the Times reports.

In January 2008, the task force commissioned six groups to study overdiagnosis and optimal screening intervals. Ultimately, it was not possible to accurately model overdiagnosis because estimates varied so widely, according to Donald Berry, a statistician at M.D. Anderson Cancer Center who was one of the modelers. Timothy Wilt, a panel member and professor of medicine at the University of Minnesota, estimated that up to 30% of cancers found by mammograms in women in their 40s are overdiagnosed. The data on screening intervals were more clear cut, and the modelers agreed that biennial mammography provided the same benefit as annual screening with half the risk of harms (Kolata, New York Times, 11/23).

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