Abstract P2-13-05: Prevalence of trastuzumab-induced cardiotoxicity in a real-world setting

Background: Trastuzumab treatment plus adjuvant or neoadjuvant chemotherapy is the standard of care for women with HER2 positive breast cancer. Despite relative low rates of cardiotoxicity observed in randomized clinical trials, trastuzumab interruption driven by LVEF reduction is a major concern in current clinical practice. Patients and methods: We retrospectively identified women with stage I-III HER2 positive breast cancer who received 12 months of trastuzumab treatment after adjuvant or neoadjuvant chemotherapy at Instituto Nacional de Cancerología (INCan, Mexico City), between 2006 and 2018. Patients were eligible if a pre-therapy MUGA scan and ≥2 subsequent follow-up scans were available. Cardiotoxicity was defined as a ≥10% LVEF reduction to a value < 50%, associated with trastuzumab interruption. Results: 910 patients were included, with a median age at diagnosis of 50 (24-85) years and a median follow up of 7 (2-11 ) years. Among the whole cohort, 10.3% of patients had diabetes, 15.4% had hypertension, 78% were obese/overweight, and 40% had positive estrogen and/or progesterone receptor status. Anthracycline-based therapy was used in 819 (90%) patients, with a median (doxorubicin equivalent) cumulative dose of 200 mg/m2 (IQR 180-240). The median baseline LVEF was 61.8% (50-88.9). In total, 94 (10.3%) patients developed cardiotoxicity, but symptomatic heart failure was observed in only 31 (3.4%) individuals. In univariable analyses, the development of cardiotoxicity was not associated significantly with cardiovascular risk factors. Conclusions: In this large single-center cohort, cardiotoxicity rates remain high, thus, interventions to minimize the risk of cardiotoxicity and trastuzumab treatment interruption should be considered. Citation Format: Calvillo-Argüelles O, Flores-Diaz D, Gonzalez-Serrano J-P, López-Rojas A, Mendoza-Galindo L, Matus-Santos J-A, Reynoso-Noverón N, Cabrera-Galeana P, Bargalló-Rocha E, Arce-Salinas C. Prevalence of trastuzumab-induced cardiotoxicity in a real-world setting [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-13-05.