Abstract
PURPOSE: While concerns regarding trastuzumab-related cardiac dysfunction (TRCD) in patients with breast cancer are increasing, there is a lack of evidence supporting the current recommendations for TRCD monitoring. We aimed to investigate the clinical predictors of TRCD in the adjuvant setting of human epidermal growth factor receptor 2-positive breast cancer patients. MATERIALS AND METHODS: From August 2003 to April 2016, consecutive 998 patients who were treated with adjuvant trastuzumab for breast cancer were retrospectively evaluated. TRCD was defined as a decrease ≥10% in left ventricular ejection fraction (LVEF), with a decline below the normal limit or symptomatic heart failure. RESULTS: Among 787 eligible patients who had complete data sets consisting of both baseline and follow-up assessment of left ventricular systolic function by echocardiography (mean age, 49.9±9.5 years), 58 (7.4%) developed TRCD. TRCD patients had lower baseline LVEF (63% [59-66] vs. 65% [61-68], p=0.016) and more frequently administered Adriamycin (98% vs. 89%, p=0.022) than those without TRCD. On follow-up echocardiography, a drop in LVEF ≥5% within the first 3 months was more frequent in TRCD patients (78.3% vs. 38.4%, p<0.001). Regardless of baseline LVEF and Adriamycin treatment, a drop in LVEF ≥5% within the first 3 months of trastuzumab administration was strongly associated with the development of TRCD (adjusted hazard ratio, 45.1[17.0-127.6], p<0.001). CONCLUSION: The overall incidence of TRCD was 7.4% in Asian breast cancer patients treated with adjuvant trastuzumab. A decline in LVEF ≥5% within the first 3 months of trastuzumab initiation was strongly associated with TRCD development in patients with breast cancer.