An ecological study of the effectiveness of mammography in reducing breast cancer mortality

Objectives. The purpose of this study was to determine the relation of screening mammography to breast cancer incidence and case fatality. Methods. In a sample of White female Medicare beneficiaries hospitalized in 1990-1991, age-adjusted breast cancer incidence and 2-year case fatality rates were estimated and compared with the frequency of mammographic screening from a population-based survey. Results. The average rates for incidence, case fatality, and mammography within 5 years in 29 states were 414/100 000, 18.8%, and 59.2%, respectively. There was a positive state-level correlation between mammography rates and incidence and an inverse correlation between mammography and case fatality. Conclusions. High screening mammography rates in some states are associated with reduced breast cancer case fatality rates, presumably as a result of diagnosis of earlier stage cancers.