Risk of Recurrence and Mortality in a Multi-Ethnic Breast Cancer Population

Background: Compared to non-Hispanic whites, African-American women tend to be diagnosed with breast cancer at an earlier age, to have less favorable tumor characteristics, and to have poorer outcomes from breast cancer. The extent to which differences in clinical characteristics account for the black/white disparity in breast cancer mortality is unclear. The purpose of this investigation was to examine the association of clinical, demographic, and treatment variables with total mortality and breast cancer recurrence by race/ethnicity in a cohort of women diagnosed with invasive breast cancer. Methods: To this end, we used data on 3890 invasive breast cancer cases diagnosed at a single medical center. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (95% CI) for the association of tumor characteristics and treatment variables with mortality and recurrence. Results: Compared to white women, black women with breast cancer presented with tumors that had worse prognostic factors, particularly higher stage, lower frequency of hormone-receptor positive tumors, and higher frequency of comorbidities. Hispanics also generally had less favorable prognostic factors compared to non-Hispanic whites. Among estrogen receptor-positive cases, blacks had roughly a two-fold increased risk of recurrence compared to non-Hispanic whites. However, ethnicity/race was not associated with total mortality. Tumor stage, tumor size, and Charlson comorbidity index were positively associated with mortality, and mammography and chemotherapy and hormone therapy were inversely associated with mortality. Conclusion: In spite of poorer prognostic factors among blacks compared whites, race/ethnicity was not associated with total mortality in our study.