Racial and Socioeconomic Disparities in Cardiotoxicity Among Women With HER2-Positive Breast Cancer

Breast cancer and cardiovascular-specific mortality are higher among blacks compared with whites, but disparities in cancer therapy-related adverse cardiovascular outcomes have not been well studied. We assessed for the contribution of race and socioeconomic status on cardiotoxicity among women with HER2-positive breast cancer. This retrospective cohort analysis studied women diagnosed with stage I-III HER2-positive breast cancer from 2004-2013. All underwent left ventricular ejection fraction assessment at baseline and at least one follow-up after beginning trastuzumab. Multivariable logistic regression was used to assess the association between race and socioeconomic status (SES) on cardiotoxicity, defined by clinical heart failure (New York Heart Association class III or IV) or asymptomatic left ventricular ejection fraction decline (absolute decrease ≥ 10% to < 53%, or ≥ 16%). Blacks had the highest prevalence of hypertension, diabetes, and increased BMI. Neighborhood-level SES measures including household income and educational attainment were lower for blacks compared with whites and others. The unadjusted cardiotoxicity risk was significantly higher in black compared with white women (OR, 2.10; 95% CI, 1.42 to 3.10). In a multivariable analysis, this disparity persisted after controlling for relevant cardiovascular risk factors (adjusted OR, 1.88; 95% CI, 1.25 to 2.84). Additional models adjusting for SES factors of income, educational attainment, and insurance status did not significantly alter the association between race and cardiotoxicity. In conclusion, black women are at increased risk of cardiotoxicity during HER2-targeted breast cancer therapy. Future etiologic analyses, particularly studies exploring biologic or genetic mechanisms, are needed to further elucidate and reduce racial disparities in cardiotoxicity.