Long-Term Safety and Real-World Effectiveness of Trastuzumab in Breast Cancer.

Trastuzumab is a milestone in the treatment of human epidermal growth factor receptor 2 positive (HER2+) breast cancer (BC), in both the early and metastatic settings. Over the last two decades, clinical trials have established the good safety profile of trastuzumab. Cardiotoxicity remains the most frequent adverse event, more commonly exemplified by an asymptomatic decline in the left ventricular ejection fraction rather than congestive heart failure. Results from several long-term (>5 years) safety analyses have been recently published, with the inherent evidence substantially confirming the findings from previous trials. The clinical experience gained over the years in the use of trastuzumab has also fueled a number of observational studies focused on the effectiveness of this drug in the real-world settings. We herein reviewed the evidence available from tree major databases, namely, PubMed, EMBASE and the Cochrane Central Register of Controlled Trials (CENTRAL), to explore and critically discuss key issues related to the long-term safety and effectiveness of trastuzumab in clinical practice.