Objective: To investigate why breast cancer mortality rates have decreased in the 1990's for white women but not for black women.
Design: Racial differences in breast cancer incidence, survival, and mortality rates were examined using regression methods and age-period-cohort models.
Setting: United States breast cancer mortality rates from 1970 through 1995, breast cancer incidence rates from 1980 through 1995, and 3-year survival rates from 1980 through 1993. The incidence and survival data are from the Surveillance, Epidemiology, and End Results Program, representing 11% of the US population, of the National Cancer Institute, Bethesda, Md.
Results: For both white and black women aged 30 to 39 years, breast cancer mortality rates began decreasing in 1987. For white women aged 40 to 79 years, breast cancer mortality rates declined after 1989, and for black women aged 40 to 69 years, mortality rates ceased increasing in the middle to late 1980s. Birth cohort trends were similar by race, but calendar period trends and survival rates differed.
Conclusions: Declines in mortality rates in women younger than 40 years reflect a favorable birth cohort trend for women born after 1948 and likely reflect changes in risk factors. The increased early detection of breast cancer by mammography and improvements in breast cancer treatment appear to be contributing to the improving mortality trends in older women, although black women appear to have benefited less than white women from early detection and treatment advances. In addition, substantial increases in survival rates for white women with regional disease have contributed to their declining mortality rates and likely reflect an increasing use of beneficial adjuvant therapy.