Parsing the mammogram guidelines

By Douglas Kamerow and Steven Woolf
Friday, November 20, 2009

Controversy continues over the mammography guidelines released Monday by the U.S. Preventive Services Task Force. As family physicians and preventive medicine specialists who have worked with the task force in many capacities over the years, we'd like to dispel some myths about the panel and try to put the recommendations into context.

First, the myths.

The task force members are not government bureaucrats. They are doctors, nurses and methodologists from universities, health systems and public health agencies who are experts in assessing preventive services. For 25 years they and their predecessors on the panel have been making evidence-based recommendations about screening tests and other preventive services using the same scientific criteria.

Although appointed by the U.S. Agency for Healthcare Research and Quality (as required by Congress), the panel is independent. It does not speak for the government or dictate health insurance coverage policies. The panel sets its own agenda and has been working on breast cancer screening recommendations for two years. That the mammography recommendations were announced during the debate on health reform is a coincidence.

The task force recommendations are not related to costs, saving money or rationing care. The panel did not consider monetary costs when reviewing evidence. The sole concern was weighing the balance of health benefits and harms of different strategies of screening to determine what is best for women's health.

Why have the recommendations, which differ little in substance from the task force's 2002 guidelines, created such a firestorm? We think it is because the statements were poorly worded; covered a controversial, touchstone issue; and were released at a time when everything is examined through the prism of health-care reform and partisan politics. In short, a perfect storm.

No one disputes the science behind the recommendations. Mammography has been proven effective in reducing deaths from breast cancer in women ages 40 to 74. All screening tests, however, involve a trade-off between benefits and harms. In younger women a lot more screening is needed to save one life because breast cancer is less common in younger women and abnormalities are harder to spot on X-rays. About 1,900 women need to be screened to prevent one breast cancer death in women ages 39 to 49, as opposed to only 377 women ages 60 to 69. That means many more overdiagnoses and false-positive results in women under 50, with the accompanying harmful side effects: unnecessary biopsies and surgeries, more X-rays and more anxiety.

There is no magic age at which the benefits of screening absolutely outweigh the harms. It is a continuum. Women of all ages should weigh the pros and cons of mammography. The task force considered this a close call, particularly for women under age 50, for whom the harms may outweigh the benefits. The panel recommended against "routine" screening of all women under 50, saying that the decision to undergo or defer screening should be made by women after discussing the benefits and risks with their doctors.

Concern about potential harms also influences the interval between mammograms. More frequent exams may find more cancers, but at the cost of more false positives and side effects. New studies done by six groups of scientists found that women get 81 percent of the mortality reduction from screening while eliminating almost half the false positives (and their side effects) if they are tested every two years instead of annually. So the task force changed its recommended screening interval from "every one to two years" to "every two years." Again, it is a continuum. Informed choice is crucial. No one knows the perfect interval, but screening at least every two years makes sense.

The task force recommendation on breast self-examination was very narrow. The panel evaluated studies of the benefit of teaching breast self-examination techniques. Such studies have found no mortality benefits from teaching, only increased false positives. Since 1987, the task force has not recommended such teaching. All women, of course, should monitor their breasts and notify their doctors if they find a lump.

We think women should ignore the political furor surrounding these recommendations. This is not a government plot to save money. No one wants insurance companies to deny coverage for mammograms. The task force is saying that the greatest benefit from screening mammography occurs for women ages 50 to 74. The task force is not against women getting mammograms in their 40s. The panel simply wants women in that age group and older women to discuss the risks and benefits with their doctors before they get tested. No one should be against that.

Douglas Kamerow, a former assistant surgeon general, is a chief scientist at the research institute RTI International and a professor of clinical family medicine at Georgetown University. From 1988 to 2001 he led Department of Health and Human Services staff that supported the U.S. Preventive Services Task Force. Steven Woolf, a professor of family medicine and director of the Center for Human Needs at Virginia Commonwealth University, was a longtime science adviser to the task force and served on the panel from 1998 to 2003.

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