Objective: To investigate why breast cancer mortality rates have decreased
in the 1990s for white women but not for black women.
Design: Racial differences in breast cancer incidence, survival, and mortal
ity rates were examined using regression methods and age-period-cohort mode
ls.
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 t
he 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 yea
rs, breast cancer mortality rates declined after 1989, and for black women
aged 40 to 69 years, mortality rates ceased increasing in the middle to lat
e 1980s. Birth cohort trends were similar by race, but calendar period tren
ds and survival rates differed.
Conclusions: Declines in mortality rates in women younger than 40 years ref
lect a favorable birth cohort trend for women born after 1948 and likely re
flect changes in risk factors. The increased early detection of breast canc
er by mammography and improvements in breast cancer treatment appear to be
contributing to the improving mortality trends in older women, although bla
ck women appear to have benefited less than white women from early detectio
n and treatment advances. In addition, substantial increases in survival ra
tes for white women with regional disease have contributed to their declini
ng mortality rates and likely reflect an increasing use of beneficial adjuv
ant therapy.