Abstract P5-14-21: Cardiotoxicity among socioeconomically disadvantaged breast cancer patients
Authors: Lu Yan , Gehr Aaron W. , Anikpo Ifedioranma , Meadows Rachel J. , Craten Kevin J. , Bannout Rim , Narra Kalyani , Lingam Anuradha , Tanna Bhavna , Ghabach Bassam , Ojha Rohit P. 
Published: March 2022

Abstract
Background Current knowledge of cardiotoxicity risk after breast cancer treatment with anthracyclines or trastuzumab is largely derived from cohorts that under-represent socioeconomically disadvantaged patients. Cardiotoxicity risk among socioeconomically disadvantaged breast cancer patients may be exacerbated considering high prevalence of smoking, obesity, and other cardiovascular disease (CVD) risk factors in this population. Estimates of cardiotoxicity risk in this population may be useful for informing surveillance and management needs during active therapy and survivorship. Therefore, we aimed to estimate cumulative incidence of cardiotoxicity after anthracycline or trastuzumab initiation among socioeconomically disadvantaged breast cancer patients. Methods We linked electronic health records (EHR) with institutional registry data from the JPS Oncology and Infusion Center, which is a Comprehensive Community Cancer Program and part of a safety-net health system that provides care for low-income, uninsured, and under-insured individuals. Eligible patients were women aged ≥18 years, diagnosed with first primary invasive breast cancer between 2013 and 2017 with follow-up through 2020, and initiated anthracyclines or trastuzumab as part of first-line therapy. Cardiotoxicity was defined as heart failure or cardiomyopathy using diagnosis codes that were confirmed by supporting documentation in EHR, or cardiac dysfunction indicated by drop of left ventricular ejection fraction (LVEF) ≥10% from baseline to &lt;55% after treatment. We used the mid-point value if LVEF was reported as a range. We used a competing-risk framework with death as the competing event to estimate overall and age-group specific cumulative incidence of cardiotoxicity with corresponding 95% confidence limits (CL). Results Our study population comprised 169 women with breast cancer (103 initiated anthracyclines and 66 initiated trastuzumab), for whom the median age was 51 years (interquartile range [IQR]: 44 - 58). The majority of women were racial/ethnic minorities (75%), uninsured or provided care through a hospital-based managed care plan for low-income qualifiers (57%), and stage I or II at diagnosis (56%). Cumulative incidence of cardiotoxicity was 22% (95% CL: 13%, 32%) at one year and 25% (95% CL: 15%, 36%) 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 for women who initiated anthracyclines. For trastuzumab initiation, cumulative incidence of cardiotoxicity at three years was 32% (95% CL: 17%, 49%) for women aged &gt;50 years and 19% (95% CL: 7.6%, 34%) for women aged ≤50 years. For anthracycline initiation, cumulative incidence of cardiotoxicity at three years was 5.5% (95% CL: 1.4%, 14%) for women aged &gt;50 years and 6.5% (95% CL: 1.7%, 16%) for women aged ≤50 years. Conclusion We observed high risk of cardiotoxicity among socioeconomically disadvantaged breast cancer patients, particularly within the first year after initiation for either anthracyclines or trastuzumab. Imprecision precludes definitive understanding whether cardiotoxicity was higher for women aged &gt;50 years but combining estimates from other socioeconomically disadvantaged populations may provide additional insight. Our estimates help extend knowledge about cardiotoxicity to under-represented populations.
Citation Format: Yan Lu, Aaron W. Gehr, Ifedioranma Anikpo, Rachel J. Meadows, Kevin J. Craten, Rim Bannout, Kalyani Narra, Anuradha Lingam, Bhavna Tanna, Bassam Ghabach, Rohit P. Ojha. Cardiotoxicity among socioeconomically disadvantaged breast cancer patients [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-14-21.