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 UC San Francisco researchers.

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, the American Medical Assn. and the American Cancer Society have recommended mammography for women in their 40s, while the National Cancer Institute has not.

Both [Karla] Kerlikowske and [Herman] 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."