Contribution of clinical and socioeconomic factors to differences in breast cancer subtype and mortality between Hispanic and non-Hispanic white women.

PURPOSE: To assess tumor subtype distribution and the relative contribution of clinical and sociodemographic factors on breast cancer survival between Hispanic and non-Hispanic whites (NHWs). METHODS: We analyzed data from the California Cancer Registry, which included 29,626 Hispanic and 99,862 NHW female invasive breast cancer cases diagnosed from 2004 to 2014. Logistic regression was used to assess ethnic differences in tumor subtype, and Cox proportional hazard modeling to assess differences in breast cancer survival. RESULTS: Hispanics compared to NHWs had higher odds of having triple-negative (OR = 1.29; 95% CI 1.23-1.35) and HER2-overexpressing tumors (OR = 1.19; 95% CI 1.14-1.25 [HR-] and OR = 1.39; 95% CI 1.31-1.48 [HR+]). In adjusted models, Hispanic women had a higher risk of breast cancer mortality than NHW women (mortality rate ratio [MRR] = 1.24; 95% CI 1.19-1.28). Clinical factors accounted for most of the mortality difference (MRR = 1.05; 95% CI 1.01-1.09); however, neighborhood socioeconomic status (SES) and health insurance together accounted for all of the mortality difference (MRR = 1.01; 95% CI 0.97-1.05). CONCLUSIONS: Addressing SES disparities, including increasing access to health care, may be critical to overcoming poorer breast cancer outcomes in Hispanics.