Mammograms No Help Before Age 50
Breast Cancer Experts Tell Women What They Should Do
Sept. 3, 2002 -- It's not a question of whether women should get regular mammograms. Experts disagree on when they should start. And the latest study showing that women in their 40s are just as likely to die of breast cancer whether or not they get mammograms only further ignites the debate.
Nearly everyone agrees that women aged 50-69 should have regular mammograms. But what about women in their 40s? The U.S. Preventive Services Task Force (USPSTF) now advises women aged 40-49 to get mammograms, but notes that the benefit is small.
Small indeed, according to a new USPSTF report in the Sept. 3 issue of the Annals of Internal Medicine. The report reviews all clinical trials of mammograms. To keep one woman younger than 50 from dying of breast cancer, the report says, it's necessary to screen almost 1,800 women for 14 years.
"Over time, mammography is almost as effective in younger women as in older women," lead researcher Linda L. Humphrey, MD, MPH, says. "The benefits are quite modest." Humphrey is associate professor of medicine at Oregon Health Sciences University and director of the Women's Health Fellowship Program at the Portland Veterans Affairs Medical Center.
There may not even be that much of a benefit, according to another study in the same issue of the Annals. The Canadian National Breast Screening study is a clinical trial in which more than 50,000 women aged 40-49 received either annual mammograms or training in self-examination with free medical follow-up. Earlier results from this trial showed that the women who got mammograms actually had more breast-cancer deaths. The latest data shows that after 11-16 years, those who got mammograms did no better than those who did not.
"What our study shows is that mammography detects more cancers. Mammography detects smaller cancers. Mammography detects cancers with less spread to the lymph nodes. Yet if you compare women aged 40-49 who got this screening with women who did not, the number of breast-cancer deaths after 13 years is precisely the same," study researcher Cornelia J. Baines, MD, tells WebMD. Baines is professor emerita at the University of Toronto.
Robert A. Smith, MD, director of breast cancer screening at the American Cancer Society, is an outspoken critic of the Canadian study.
"Despite the best intentions, some studies have such serious flaws that their findings simply do not reflect the underlying truth," Smith says in a statement. "The goal of screening is to reduce the incidence rate of advanced disease, so that treatment begins earlier. The Canadian investigators failed to accomplish this, so we see no difference in their death rates."
A study recently co-authored by Smith compared the medical records of Swedish women who actually got mammograms with those of women who did not. It found a 45% reduction in breast cancer in the screened women.