Factors for time to trastuzumab-induced cardiotoxicity in breast cancer patients

Trastuzumab is a drug used for the treatment of metastatic breast cancer patients. Due to blockage of the human epidermal growth factor receptor 2 signaling in cardiac myocytes, cardiotoxicity has been observed. There are many studies that investigated risk factors for trastuzumab-induced cardiotoxicity, but no study has been published for factors on the time to cardiotoxicity. This study aimed to investigate the factors for the time to occur trastuzumab-induced cardiotoxicity. From January 2014 to December 2015, a retrospective study was performed with breast cancer patients who were treated with trastuzumab. Associations between presence of and time to cardiotoxicity and various factors were analyzed. Based on multi-variate models, it was found that baseline left ventricular ejection fraction (LVEF) < 62.5% (AHR 5.96, 95% CI 2543-13.95) and anthracycline-based chemotherapy (AHR 7.90, 95% CI 1.05-59.71) were significant factors for time to cardiotoxicity after adjusting other confounding factors. Multivariate analysis also showed that BMI = 23 kg/m(2) and baseline LVEF value < 62.5% increased cardiotoxicity 3.0 and 6.6 times, respectively. Our study showed that BMI = 23 kg/m(2), LVEF < 62.5%, and anthracycline-based chemotherapy were associated with time to trastuzumab-induced cardiotoxicity. Thus, close monitoring of cardiac function is recommended especially for patients using the above risk factors.