The impact of race/ethnicity on survival in secondary triple negative breast cancer

Objective: To identify if treatments used for secondary triple negative breast cancer are associated with survival differences by race/ethnicity. Background: Survival in women with secondary breast cancer, and those with triple negative breast cancer (TNBC), is worse for young women, especially non-Hispanic (nH) Black women. We hypothesize this is related to treatment received. Methods: Females, aged 15-50 years, diagnosed with a TNBC during 2003-2019 were identified using the California Cancer Registry. Multivariable logistic regression compared characteristics of secondary vs primary TNBC. Multivariable Cox proportional hazards regression models evaluated associations of secondary vs primary TNBC on overall survival (OS) and breast cancer specific survival (BCSS). Analyses were stratified by race/ethnicity. Results: Of 682 women with a secondary TNBC, 48.5% were nH White, 11.3% were nH Black, and 31% were Hispanic. All women with a secondary TNBC (vs primary TNBC) were more likely to receive a mastectomy and non-anthracycline based chemotherapy. NH White women were less likely than women of other races/ethnicities to have axillary lymph node dissections. Hispanic and nH White women with a secondary (vs primary) TNBC experienced worse OS and BCSS, which was not seen in nH Black and Asian/Pacific Islander women (Figure 1). Conclusion: While treatments were similar for secondary vs primary TNBCs by race/ethnicity, Hispanic and nH White women with secondary TNBC experienced worse survival. Our findings suggest that tumor biology, rather than treatment, differs in secondary TNBC, warranting different treatment algorithms to improve outcomes. Figure 1: Multivariable Adjusted Cox Proportional Hazard Ratios for Overall Survival and Breast Cancer Specific Survival for Secondary compared to Primary Triple Negative Breast Cancer by Race/Ethnicity Overall Survival Breast Cancer Specific Survival