Although mammography for women in their 50s and 60s can reduce deaths from breast cancer by nearly a third, the technique provides no measurable improvement in survival among younger women, according to researchers at the University of California, San Francisco.
Breast cancer screening for women under 50 has been a hotly debated subject because previous studies of its efficacy have been small and yielded mixed results. Reflecting that confusion, both the American Medical Association and the American Cancer Society have recommended mammography for women in their 40s, while the National Cancer Institute has not.
Dr. Karla Kerlikowske and her colleagues at UCSF attempted to overcome that problem by combining the data from 13 separate studies completed between 1966 and 1993.
They report in today’s Journal of the American Medical Association that the new analysis shows mammography “does not significantly reduce mortality in women aged 40-49 years.” The study also concludes that, in older women, a mammogram every other year is just as effective as a yearly examination.
“To everyone who looks at it from a scientific viewpoint, (the question of mammography before age 50) is a closed issue,” said Dr. Herman Kattlove who heads a Rand Corp. group studying another aspect of breast cancer.
Both Kerlikowske and Kattlove emphasized, however, that the debate over screening younger women applies only to the general population and not to women with a high family risk of breast cancer. Such women, Kattlove said, “ought to have mammography screening at earlier ages.”
Neither the AMA nor the ACS is backing down from their previous positions. “Because of the complexity of the issues involved, the variation in design and conduct of the studies cited, (and) the fact that most of the studies cited were conducted in countries other than the United States (where mammography technology is not as advanced as in the United States) … these reviews should not be used alone as the basis for denying screening mammograms to women aged 40-49,” said Dr. James Allen, vice president of science, technology and public health standards for the AMA.
A cancer society spokesman said the agency had “actively reviewed” the same studies gathered in the UCSF paper and found no reason to change its recommendations.
Breast cancer strikes an estimated 180,000 women each year, killing 46,000.
In a meeting of the National Cancer Advisory Board in Washington Tuesday, Samuel Broder, head of NCI, said the number of breast cancer deaths declined 6 percent from 1989 to 1992 - the largest short-term drop since 1950 - largely because of better treatment and more women being screened.