Predictors of cardiotoxicity in patients with early breast cancer treated with doxorubicin and/or trastuzumab: Implications of race/ethnicity and insurance status.

12021 Background: Approximately 4.1 million women in the US are living with breast cancer 1 . Cardiac dysfunction is a significant adverse effect of commonly used breast cancer therapies like doxorubicin (D) and trastuzumab (T). The cardiotoxicity (CTox) associated with these agents manifests as a reduction in left ventricular ejection fraction (LVEF) with or without signs and symptoms of heart failure. Purpose: Identify high-risk populations susceptible to developing CTox, with a focus on identifying individuals who could potentially benefit from the early initiation of empiric cardioprotective therapies. Methods: We investigated the relationship of race/ethnicity, insurance status, treatment regimen and comorbidities including hypertension (HTN), hyperlipidemia (HLD), diabetes mellitus (DM), tobacco use, BMI, age, and radiation therapy on the development of CTox from D and/or T. A total of 133 newly diagnosed stage I-III invasive breast cancer patients were enrolled in a prospective clinical trial (2013-2017) and received standard of care D and/or T based systemic therapy. Echocardiogram data was collected every 6 months for two years and then based on clinical need for a total of six years. CTox was defined as a >10% drop in LVEF, and/or LVEF <50%. Results: Our study included a population of 133 patients comprising Black (22%), White (77%), and Hispanic (1.5%) individuals. Among these patients, 32 developed CTox (Black 41%, White 19%, Hispanic 50%). Of all patients, 29% had State insurance while 71% had Private insurance. Prevalence rates for comorbidities were as follows: HTN (41%), HLD (32%), DM (13%), and tobacco use (36%). In a univariate logistic regression model, race/ethnicity, HTN, insurance status, and tobacco use were most strongly associated with Ctox. When controlling for tobacco use and HTN, race/ethnicity was not significantly associated with Ctox. However, direct comparisons of levels of race/ethnicity showed that Black patients were more likely to develop Ctox when compared to White patients (OR 2.60, 95% CI = 1.01-6.65, P = 0.045). HTN patients were also more likely to develop Ctox, when controlling for ethnicity and tobacco use (OR 2.62, 95% CI = 1.10-6.43, P = 0.031). In a separate multivariate analysis, we examined insurance as a surrogate for socioeconomic status. State insurance was associated with an increased risk of developing CTox when controlling for race/ethnicity and HTN (OR 3.73, 95% CI = 1.47-9.58, P = 0.006). Furthermore, in all models, HLD, DM, BMI, age, and radiation field were not found to be significantly associated with increased CTox. Conclusions: In our well characterized population of patients with stage I-III breast cancer, who were prospectively followed and received standard of care systemic therapy, we observed an association between insurance status with increased risk of CTox from treatment regimen.