Behind the Cancer Headlines®

December 2, 2008

Among women younger than 40 years, black women have a higher incidence of breast cancer than white women. However, among women older than 40 years, white women have a higher incidence than black women. This incidence rate "crossover" appears reproducible and reliable.

Several previous studies have reported the age-related crossover in black and white women, but some of them have suggested that it was an artifact.

In the current study, published in the Journal of the National Cancer Institute, William Anderson, M.D., of the National Cancer Institute in Bethesda, Md., and colleagues reviewed data from 440,653 patients with breast cancer from the Surveillance, Epidemiology, and End Results (SEER) database.

Among women who were younger than 40 years, the incidence of breast cancer was 15.5 breast cancers per 100,000 woman-years in black women compared with 13.1 in white women. Among women who were older than 40 years, the incidence was 239.5 breast cancers per 100,000 woman-years in black women compared with 281.3 in white women.

"Although this ecologic study cannot determine the individual-level factors responsible for the racial crossover in vital rates, it confirms that the age-related crossover in breast cancer incidence rates between black and white ethnic groups is a robust age-specific effect that is independent of period and cohort effects," the authors write.

SOURCE:
Journal of the National Cancer Institute, December 9, 2008