Cardiotoxicity among socioeconomically marginalized breast cancer patients

Purpose Evidence of cardiotoxicity risk related to anthracycline or trastuzumab exposure is largely derived from breast cancer cohorts that under-represent socioeconomically marginalized women, who may be at increased risk of cardiotoxicity because of high prevalence of cardiovascular disease risk factors. Therefore, we aimed to estimate cardiotoxicity risk among socioeconomically marginalized breast cancer patients treated with anthracyclines or trastuzumab and describe clinical consequences of cardiotoxicity. Methods We linked electronic health records with institutional registry data from a Comprehensive Community Cancer Program within a safety-net health system. Eligible patients were adult females, diagnosed with first primary invasive breast cancer between 2013 and 2017, and initiated anthracyclines or trastuzumab as part of first-line therapy. We estimated cumulative incidence (risk) of cardiotoxicity with corresponding 95% confidence limits (CL) using the Aalen-Johansen estimator with death as competing risk. Results Our study population comprised 169 women with breast cancer (103 initiated anthracyclines and 66 initiated trastuzumab). Cumulative incidence of cardiotoxicity was 21% (95% CL: 12%, 32%) at one year and 25% (95% CL: 15%, 35%) at three years among women who initiated trastuzumab, whereas cumulative incidence was 3.9% (95% CL: 1.3%, 8.9%) at one year and 5.9% (95% CL: 2.4%, 12%) at three years among women who initiated anthracyclines. More than half of patients with cardiotoxicity experienced interruption of cancer treatment. Conclusion Our findings suggest high risk of cardiotoxicity among socioeconomically marginalized breast cancer patients after initiation of anthracyclines or trastuzumab. Strategies are needed for optimizing cancer treatment effectiveness while minimizing cardiotoxicity in this population.