Racial differences in breast cancer survival: the interaction of socioeconomic status and tumor biology.

OBJECTIVE: Our purpose was to evaluate the effect of sociodemographic and clinical variables on survival rates of African-American and white women with breast cancer. STUDY
DESIGN: Between 1988 and 1992 the Metropolitan Detroit Cancer Surveillance System Identified 10,502 women (82% white and 18% African-American) in whom invasive breast cancer was diagnosed. Cox proportional hazards regression was used to estimate the relative risk of death for African-Americans compared with whites after controlling for variables believed to influence survival.
RESULTS: African-American women were more likely than white women to have tumors that were of a more advanced stage, a higher grade, and hormone receptor-negative. After controlling for age, tumor size, stage, histologic grade, census-derived socioeconomic status, and the presence of a residency training program at the treatment hospital, the relative risk of dying for African-Americans compared with whites was 1.68 (95% confidence interval, 1.27-2.23) for women less than 50 years of age, and 1.33 (95% confidence interval, 1.13-1.56) for women older than 50 years of age.
CONCLUSIONS: Known factors that predict survival differences between African-Americans and whites are more prevalent among women less than 50 years of age, emphasizing the need to focus more attention on public health efforts directed toward younger women.