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.