Recent trends in breast cancer incidence, mortality, and mammography.

The recent trends in mammography, and in breast cancer incidence and mortality, demonstrate the impact of an effective cancer control effort. The number of women over age 40 years who have ever had mammography has increased over 200% since 1980. Concomitantly, breast cancer incidence has increased about 32%, with nearly all of the increase in early stage disease. Analytic studies of these changes have demonstrated persuasively that the vast majority of this increase is temporary and is attributable to the lead-time afforded by mammography. As a result of this early detection and treatment of breast cancer, mortality has begun to decline in 1991-92. Although the search for practical preventive measures should continue, the benefits of early detection can be realized now. Further research is needed to define age groups most appropriately screened and the optimum intervals for screening.