Patterns of cardiac monitoring and outcomes in patients with HER2-positive breast cancer treated with a trastuzumab-based regimen in a safety-net system.

Abstract

e24027 Background: Targeting HER-2 receptor with monoclonal antibodies is the mainstay of treatment in HER2-positive breast cancer and can result in cardiotoxicity, most notably a reduction in left ventricular ejection fraction (LVEF). The FDA label for trastuzumab recommends LVEF assessment at baseline, every 3 months during treatment, and at 12 months after completing treatment. Resource limitations in safety-net settings, particularly in the absence of an established cardio-oncology program, may impact frequency of cardiac monitoring and contribute to disparities. We aimed to characterize patterns of monitoring with transthoracic echocardiogram (TTE) and outcomes among breast cancer patients treated in a safety-net system. Methods: Parkland Health is the safety-net system for Dallas County and provides care to a primarily underinsured, minority-enriched population. Electronic health records (EHR) of women diagnosed with Stage I-III HER2 positive breast cancer and treated with trastuzumab between January 2015 to January 2020 were reviewed. We utilized Chi-square test and t-test as well as linear mixed effects models to analyze patient outcomes and changes in echocardiogram parameters, respectively. Results: A total of 76 patients undergoing treatment with curative intent were included. In our cohort, mean (SD) age at diagnosis was 50 (9) years, 17 (22%) were Black, 43 (57%) were Hispanic, and 50 (66%) were uninsured. 100% of patients received trastuzumab, and 63 (83%) received dual anti-HER2 therapy (trastuzumab-pertuzumab). Baseline TTE was performed prior to or at the time of first treatment cycle in 41 (54%) patients. 71 (93%) patients received at least 3 months of therapy, with only 26 (37%) receiving TTE screening every 3 months while on therapy. Race and insurance status were not significantly correlated with undergoing baseline TTE. While there was no significant decrease in LVEF during anti-HER2 treatment, two patients developed symptomatic heart failure requiring hospitalization. Two additional patients met criteria for moderate asymptomatic cancer-therapy related cardiac dysfunction, defined by LVEF reduction of greater than 10% to an LVEF of less than 49%. Conclusions: Within our safety-net system, nearly half of our patient population did not receive baseline TTE screening prior to receiving cardiotoxic chemotherapy. As sociodemographic factors were not significantly associated with this outcome, there may be larger system-level barriers towards obtaining proper screening. Establishing a dedicated cardio-oncology department and recruiting dedicated technicians in oncology clinics may enhance adherence to recommended screening guidelines.