Racial differences in breast cancer survival in a large urban integrated health system

African American (AA) women are known to have poorer breast cancer survival than whites, and the differences may be related to underlying disparities in their clinical presentation or access to care. This study evaluated the relationship between demographic, treatment, and socioeconomic factors and breast cancer survival among women in southeast Michigan.

The population included 2387 women (34% AA) with American Joint Committee on Cancer stage I to III breast cancer who were treated at the Henry Ford Health System (HFHS) from 1996 through 2005. Linked data sets from the HFHS, the Metropolitan Detroit Cancer Surveillance System, and the US Census Bureau were used to obtain demographic and clinical information. Comorbidities were classified with the modified Charlson comorbidity index (CCI). Economic deprivation was categorized with a census tract-based deprivation index (DI), which was stratified into 5 quintiles of increasing socioeconomic disadvantage.

Compared with whites, AA women were significantly more likely to have larger, hormone receptor-negative tumors and more comorbidities and to reside in an economically deprived area. In an unadjusted analysis, AAs had a significantly higher risk of death (hazard ratio [HR], 1.36; 95% confidence interval [CI], 1.16-1.59); however, after adjustments for clinical (age, stage, hormone receptor, and CCI) and societal factors (DI), the effect of race was not significant (HR, 1.13 [95% CI, 0.96-1.34] , and HR, 0.97 [0.80-1.19] respectively).

Racial differences in breast cancer survival can be explained by clinical and socioeconomic factors. Nonetheless, AA women with breast cancer remain disproportionately affected by unfavorable tumor characteristics and economic deprivation, which likely contribute to their increased overall mortality.