Abstract PD8-02: Tumor subtype and survival differences between Hispanic and non-Hispanic white breast cancer patients in the California cancer registry
Authors: Martinez ME , Cress R , Gomez S , Rodriguez D , Cook LS , Schwab R , Nodora JN , Porter P , Li C 
Published: March 2017

Background: Prior studies show that Hispanic breast cancer patients are more likely than non-Hispanic white (NHW) women to be diagnosed with triple negative tumors but data on other subtypes are limited. Published data on survival differences between Hispanics and NHW breast cancer patients are inconsistent and vary depending on the covariates included in the multivariate models. We assessed differences in the distribution of the major tumor subtypes of breast cancer, as well as subtype-specific survival, between Hispanic and NHW patients according to nativity, and age and stage at diagnosis.

Methods: We used data from the population-based California Cancer Registry to include female invasive breast cancer cases diagnosed between 2004 and 2013 with follow-up through December 31, 2013, resulting in 90,236 total cases (69,693 NHW and 20,543 Hispanics). Tumor subtypes were classified into four categories: hormone receptor positive and HER2 negative (HR+/HER-), HR+/HER2+, HR-/HER2+, and triple negative (HR-/HER2-). Logistic regression was used to estimate differences in distribution of subtype between Hispanic and NHW women. Cox proportional hazard models were used to estimate differences in survival for Hispanics and NHWs by subtype, adjusting for clinical and sociodemographic characteristics.

Results: Compared to NHW patients, Hispanic women were more likely to be diagnosed with tumors that were HR+/HER2+ (OR=1.22; 95% CI, 1.16-1.29), HR-/HER2+ (OR=1.37; 95% CI, 1.29-1.47), and triple negative (OR=1.27; 95% CI, 1.21-1.34) than HR+/HER2-. Foreign-born Hispanics had a higher odds of having HER2+ than HR+/HER2- tumors compared to NHW women (OR=1.29 for HR+/HER2+ and OR=1.50 for HR-/HER2+); these differences were less pronounced among U.S.-born Hispanics (OR=1.04 for HR+/HER2+ and OR=1.16; 95% CI, 1.06-1.26 for HR-/HER2+). In age-adjusted models, Hispanic women had higher breast cancer mortality than NHW women (HR=1.23; 95% CI, 1.17-1.30), which was consistent across all tumor subtypes. However, the mortality differences disappeared after adjustment for clinical, sociodemographic characteristics, and marital status.

Conclusions: Hispanic women were more likely than NHWs to be diagnosed with triple negative breast cancer as well as tumors overexpressing HER2 than HR+/HER2- tumors. This pattern held true when stratified by nativity, although higher ORs for HER2+ tumors among foreign-born than U.S.-born Hispanic women were observed. Within each subtype, Hispanics had 20%-30% higher mortality than NHW, which appeared to be explained by a combination of sociodemographic and clinical factors.

Citation Format: Martinez ME, Cress R, Gomez S, Rodriguez D, Cook LS, Schwab R, Nodora JN, Porter P, Li C. Tumor subtype and survival differences between Hispanic and non-Hispanic white breast cancer patients in the California cancer registry [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr PD8-02.