Recent trends in breast cancer mortality among white and black US women.

OBJECTIVES: Time trends in breast cancer mortality were analyzed from 1970 to 1992 among White and Black US women aged 25 and over. METHODS: Mortality data from the National Center for Health Statistics were summarized within three periods 1970 to 1979, 1980 to 1988, and 1989 to 1992. The annual change was calculated as the average yearly percentage of change based on the logistic model. RESULTS: For White women of all ages, breast cancer mortality decreased by 1.6% (95% confidence interval = -2.0%, -1.1%) per year on average during 1989 to 1992, in contrast to the flat mortality rates observed during the 1970s and a 0.5% average annual increase during 1980 to 1988. The decline was observed for White women under age 60, among whom breast cancer mortality had been decreasing, and for White women aged 60 to 79, among whom breast cancer mortality had been increasing, but it was not observed among Black women. CONCLUSIONS: The long-awaited decline in US breast cancer mortality has finally appeared, although only among White women. The possible contributions are changes in inherent risk of disease, changes in treatment effectiveness, and increased use of screening mammography.