Real-world data of cardiotoxicity during long-term therapy with trastuzumab in human epidermal growth factor receptor-2-positive metastatic breast cancer

Abstract

Introduction/Objective. This study aims to investigate the cardiotoxicity of long-term therapy with trastuzumab in patients with HER2 positive metastatic breast cancer. Methods. A total of 48 patients with metastatic HER2 positive breast cancer were analyzed. The patients received long-term trastuzumab (time of application was longer than 20 months). The analyzed characteristics of the patients were: age, initial stage of the disease, application of anti-HER2 therapy and anthracyclines in the adjuvant setting, the number and type of applied systemic therapies concomitant with trastuzumab in the metastatic setting. Cardiac toxicity was assessed using left ventricular ejection fraction (LVEF) values at three time points: at the beginning, in the middle, and at the end of treatment period for each patient separately. Results. In 17 (35.4%) patients the trastuzumab treatment was temporary discontinued. The average time of trastuzumab therapy interval was 52.2 ? 23.5 months. The mean LVEF values were 66.73 ? 7.02%, 64.62 ? 5.7% and 63.44 ? 6.1%, respectively. The mean values of LVEF differed significantly in the observed three time points (F=4.9 p=0.009). Post hoc pairwise comparison, using Bonferonni correction, confirmed significantly lower mean LVEF values at the end point (at the end of treatment) compared with the mean LVEF values at the beginning of anti-HER2 treatment (p = 0.019), but within the reference range of LVEF ?50%. Conclusion. The data confirm good safety profile of long-term trastuzumab therapy in HER2 positive metastatic breast cancer patients considering cardiotoxicity.