Evidence of breast cancer mortality reduction: aggressive screening in women under age 50.

Five year follow-up data for breast cancer screening of 10,531 self-selected women are presented. The data are compared with the Health Insurance Plan of New York population and it appears that the magnitude of the mortality reduction in these two populations is similar. However, contrary to the New York findings, the data demonstrate that the benefit to screening this population was maximal in women under age 50. No breast cancer deaths have been recorded in 5 years of follow-up in this younger population (6,030 individuals). Interpretation of the data is that aggressive screening for breast cancer can favorably alter breast cancer mortality, particularly in younger women.