Rates of trastuzumab-associated cardiotoxicity in patients with HER2-positive breast cancer at a tertiary cancer centre.

e12030 Background: Human epidermal growth factor receptor 2 ( HER2) is overexpressed in 15-25% of breast cancers and associated with decreased rates of survival. Trastuzumab (TZ) is a humanized monoclonal antibody that binds against HER-2 and improves both disease free and overall survival in the adjuvant setting. A side effect of TZ is reversible cardiotoxicity(CT), which can lead to early termination of TZ. The rates of TZ associated CT seen in trials range between 1-16%. These rates may not be representative of clinical practice. Our aim is to identify the rate of TZ-associated CT and the rate of early discontinuation of TZ associated CT at the Juravinski Cancer Centre (JCC), in Hamilton, Ontario. Methods: Patients treated with adjuvant TZ between 2006-2013 at JCC were identified using JCC pharmacy data and included in this audit. We examined patient charts for relevant clinical-pathologic variables, cardiac Results: Results are shown in the table below. Conclusions: In conclusion, we found that rates of CT were higher at JCC than in clinical trials. This is not unexpected as patients with known cardiac risk factors and history of cardiac disease were excluded from most clinical trials. Strategies to optimize cardiac risk factors and management of CT are needed. We have opened a cardio-oncology clinic at JCC and initiated a clinical trial examining the feasibility of ongoing TZ therapy in the setting of mild DLVEF. [Table: see text]