BETHESDA, Md. -- New analyses of data from around the world have failed to show that women under age 50 benefit from mammograms, confirming a Canadian study published late last year.
The new data, reported at a two-day meeting of experts on mammography sponsored by the National Cancer Institute, add
fuel to a growing debate over whether the cancer institute and the American Cancer Society should change their guidelines recommending that women in their 40s have mammograms every one to two years to detect cancers before they are big enough to feel.
Both groups' guidelines were is sued a decade ago and were based on inferences rather than hard data. Last fall, they were thrown into doubt by results from a large Canadian study that many specialists had expected would prove that younger women live longer if they have mammograms.
Instead, the study found that the women in their 40s who had mammograms had the same death rate from breast cancer as those who did not have the screening. But all the studies found a substantial benefit in mammograms for women 50 and over. The theory is that younger women have denser breasts, making mammograms more difficult to read.
Medical experts had hoped that other studies, or perhaps an analysis that combined data from all the world's large studies, would justify the guidelines recommending regular screenings for younger women. Instead, with the new data reported Wednesday and yesterday, that hope was --ed.
This new development puts women in their 40s in an agonizing position since the official recommendation that they have regular mammograms remains even though the emerging scientific consensus seems to be turning against this advice. Doctors and consumer advocates at the meeting urged that women be presented with all the conflicting information about mammograms and be given the chance to make their own decisions. Mammograms cost $50 to $150.
Researchers also said that even for women under 50 who have special risk factors, such as a family history of breast cancer, no data are available that can answer whether a mammogram is beneficial.
Dr. Suzanne Fletcher, a co-editor of the Annals of Internal Medicine and chairwoman of the cancer institute's meeting, said she and four others who were asked to convey the meeting's results to the President's Cancer Advisory Board in March concluded that the effectiveness of mammograms in younger women has not been demonstrated.
In studies that have followed women in their 40s for five to seven years, she said, "There is no reduction in breast cancer mortality."
She added that in the few studies that have followed women for 10 to 12 years, "There is an uncertain and at best marginal reduction in breast cancer mortality." It is not clear whether the test would turn out to save lives if researchers continued to follow the women in these studies.
"This is really bad news for women," said Cindy Pearson of the National Women's Health Network.
After being told for years that mammograms would save their lives, she said, women in their 40s now have essentially nothing they can do to lower their risk of dying from breast cancer.
The National Women's Health Network is advising women not to have mammograms until they are 50.