The Stockholm Mammographic Screening Trial: Risks and benefits in age group 40-49 years

This article presents updated data on breast cancer mortality for women under age 50 from the Stockholm Mammographic Screening Trial, as well as a review of some side effects associated with screening in this age group. Approximately 40,000 women aged 40-64 (14,842 aged 40-49 years) were randomized to a trial of breast cancer screening by single-view mammography alone; 20,000 women (7,103 aged 10-49) were randomized to a control group. In the 40-49 age group, 24 and 12 breast cancer deaths were found in the study and control groups, respectively, after 11.4 years of follow-up. The relative risk of breast cancer death in screened to nonscreened women was 1.08 (95% confidence interval: 0.54-2.17). The rates of benign surgical biopsies, false positives, and follow-up costs were higher among women under age 50. Large overview studies are needed, however, to determine whether mammography screening consistently reduces mortality in women 40-49 years of age. Side effects such as costs and public aspects of mammography screening in this age group also warrant further study.