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.