Mammography Controversy

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Women's Health Activist Newsletter
March/April 1997

by Cynthia Pearson

NIH Consensus Panel Recommends Women Make Individual Decision

After nearly four years of on-again, off-again debates, mammography is once again hot news in the wake of a controversial new report by a National Institutes of Health Consensus Panel. The Panel recommended insurance coverage of screening mammography for women in their forties but did not recommend that all women in their forties be screened regularly. The Panel's less than enthusiastic support for mammography screening of young women was somewhat surprising, as the Panel was convened at the request of Richard Klausner, the new NCI Director who has been pressured by Congress to come out in favor of routine screening for women in their forties.

The Panel's recommendations were instantly controversial when the report was released in an NIH auditorium in Bethesda, Maryland in late January. Radiologists responded vehemently, claiming that the report was a "death sentence" for thousands of women and that panel members were hand-picked by NC1 scientists biased against mammography. A well-known Swedish radiologist, Lazlo Tabar, rushed to the microphone to claim that an epidemiologist critical of mammography "didn't know how to count." NWHN Executive Director Cindy Pearson staunchly defended the panel's refusal to make a blanket recommendation when the data doesn't warrant one, stating, "It is way past time to stop giving women simplistic information in order to control their behavior. Women deserve to know everything That researchers know, even if it is not Clear cut." (In 1993, the Network issued  recommendation that women begin Screening at the time of menopause, or age 50, whichever came first.) Other consumer advocacy organizations including the Center for Medical Consumers and the Long Island One in Nine Breast Cancer Group commented favorably on the Panel's work. Further fueling the controversy, NCI's Director publicly disagreed with the conclusions of the Consensus Panel.

The radiologists' point of view; Klauser's renunciation of the panel's decision; and the decision of the American Cancer Society to continue recommending screening for women in their 40's galvanized the Senate, led by all nine women Senators, to pass a nonbinding resolution in early February, strongly encouraging NCI to recommend screening for women in their forties. The measure passed by a vote of 98 to 0, demonstrating either that every Senator is deeply concerned about breast cancer, Or that at least some Senators perceived this as a no risk, no thought way to be seen as supportive of women. At a Senate hearing shortly after the vote, Fran Visco, President of the National Breast Cancer Coalition, confronted Senators, saying "Let's save outrage for the fact that we don't know how to prevent this disease, how to detect it truly early, or what to do for an individual women once we do find it." So far, we've seen no indications of a broader legislative response.

What Are the Facts behind the Controversy?

The need for good breast cancer screening tests for women under 50 is real. Over 22% of all cases of breast cancer are diagnosed in women under 50.  Although the average 40 year old women has less than a 2% chance of being diagnosed with breast cancer in her forties and only a 0.3% chance of dying while in her forties, breast cancer is still the most common cause of death for women in this age group. African American women are especially affected by he need for a good screening test for younger women; on average they are years younger when diagnosed with breast cancer than are white women.

Eight randomized controlled trials have evaluated the ability of mammography screening to save women's lives. Taken together, these trials show a significant benefit for women 50 to 69 years. Within seven years after beginning screening, women are 30% less likely to die of breast cancer, a benefit which seems to persist as long as women are followed (nearly 20 years in the oldest study). These trials have also included women under age 50, and until now, did not show a life saving benefit for younger women. Now that several trials have followed women for 10-14 years and even longer, there is a statistically significant mortality benefit for women who were in their forties when screening began. Published estimates of this benefit show a decrease of about 16%. At the Consensus Conference estimates based on newly reported data were closer to 18%.

In most cases when a group of randomized controlled trials shows a statistically significant reduction in mortality in the screened population, recommendations are made for routine screening. But in this case, the Consensus Panel looked at the data and came up with a different recommendation. One major reason for their decision was the length of time it took for any trial to find a benefit in women in their forties. If it takes 10 or more years to see a decrease in mortality in women who began screening at age 40 (or 45 in at least one trial), then it is likely that at least some of that benefit is from screening that took place after age 50.

The Panel also took into account that even though a small mortality benefit had been demonstrated, the test was clearly not as good in younger women as in older, partly because breast tissue becomes less dense with age, particularly after menopause. While mammography misses about 10% of invasive cancers in women over 50, it misses 25% of invasive cancers in women in their forties. Women in their forties are at least as likely as older women to be told they have a suspicious mammogram, but are much less likely to have a cancer found during follow-up—the mammogram is more likely to give a false positive result. Another factor considered by the Panel is the likelihood that women in their 40's will be diagnosed with ductal carcinoma in situ (DC1S). It is not completely clear yet whether this is bad news or good news.

Only invasive cancer has the capacity to metastasize and kill. If all DC1S were destined to evolve into invasive cancer, catching it at the pre-invasive stage would be beneficial. But studies have shown that the majority of DCIS does not develop into invasive cancer, leading the Panel to raise the issue that routine mammography screening for women in their 40's may lead to significant unnecessary treatment including bilateral mastectomies. The Panel also raised the issue of the theoretical risk of cancer caused by mammography. Although it is well established that higher doses of radiation at earlier ages can cause breast cancer, the risk from low dose mammography starting at age 40 is not established.

What You Can Do

We encourage women to get as much information as possible. We are preparing a fact sheet about mammography, which will expand on the information in this article. We also encourage women to become active with groups working for more research on alternatives
to mammography, more information about the causes of breast cancer,
better treatments, safe prevention and access to health care for all.
The final version of the Consensus Statement should be available from NIH in late March. Call 1-800-4-CANCER.

Cynthia Pearson is the Network's Executive Director


Date Published: 
Mon, March 03, 1997