Cardiotoxicity risks of adjuvant trastuzumab in Asian breast cancer patients

Abstract

561 Background: Adjuvant trastuzumab (T)-based chemotherapy has been shown to reduce relapse and improve survival in breast cancer patients but has been associated with increased risks of cardiotoxicity. Our study aims to define the incidence and severity of cardiotoxicity amongst Asian breast cancer patients. Methods: This is a retrospective review of patients who have received adjuvant T from June 2005 to 2007. Cardiotoxicity was defined as a drop in left ventricular ejection fraction (LVEF) to less than 50% and/or reduction of > 10% of baseline. Cardiovascular (CVS) risk factors were defined as having a family history or presence of CAD, hypertension, diabetes mellitus, hyperlipidemia and smoking. We used pair sampled t-test to evaluate the mean LVEF change and Chi-square test to evaluate the association of cardiotoxicity and demographics. Results: There were 179 female patients. Cardiotoxicity was reported in 70 (39.1%), of whom 59 had asymptomatic decline in LVEF and 11 experienced CHF. Mean LVEF, comparing various time points (3, 6, 9 and 12 months) against baseline showed statistically significant decline (p<0.05). T was withheld (n=33) due to asymptomatic decline in LVEF (n=24), symptomatic heart failure (n=4) and both (n=5). Twenty-one with resolution of CHF (n=7) or LVEF recovery (n=14) were rechallenged. Cardiotoxicity recurred in 9 - asymptomatic decline in LVEF (n=8) and recurrent CHF (n=1). There were no cardiac-related deaths. Neither patient demographics nor CVS risk factors predicted for cardiotoxicity. Conclusions: This is one of the largest series reported in Asians receiving T. As previously reported, T-induced cardiotoxicity resulted in mostly asymptomatic reversible decline in LVEF. Our incidence of cardiotoxicity appeared higher (39.1%) in Asians and more importantly, almost half of the patients experienced cardiotoxicity upon rechallenge. It would be prudent to explore whether there is any difference in susceptibility to T-induced cardiotoxicity between the different races. [Table: see text] No significant financial relationships to disclose.