Long-term tolerance and cardiac function in breast cancer patients receiving trastuzumab therapy

We examined the long-term clinical tolerance and cardiac safety of trastuzumab treatment in ninety-four female patients diagnosed with breast cancer with human epidermal growth factor receptor 2 (HER-2) overexpression. Electrocardiography (ECG) was monitored throughout trastuzumab treatment, and left ventricular ejection fractions (LVEFs) were estimated using echocardiography prior to treatment with trastuzumab and every 3 months after its first application. The duration of trastuzumab treatments ranged from 3 to 60 months. Declines in LVEF ≥ 15% were seen mainly after 3-15 months of trastuzumab treatment, and LVEF was lowest at 15 months, which coincided with the largest decline in LVEF from baseline. Spearman correlation coefficients indicated that accumulation of anthracycline, the use of cyto/cardioprotective drugs (CPD) and the duration of trastuzumab treatment were all associated with the change of LVEF, and there was a strong correlation between these factors and the change of LVEF (ρ=0.81, ρ=0.734 and ρ=0.777 respectively). These results indicate that significant decreases of LVEF may be seen after 3-15 months of trastuzumab treatment, but that there is a favorable benefit-risk ratio for patients undergoing long-term trastuzumab treatment.