Controversies in the use of adjuvant trastuzumab (Herceptin).

Over-expression of the human epidermal growth factor receptor 2 (HER2) protein, amplification of the HER2 gene or both occur in 15-25% of breast cancers and are associated with aggressive tumour behaviour. Trastuzumab (Herceptin), a humanized murine monoclonal antibody against the HER2 protein, has been shown to benefit patients with HER2-positive metastatic breast cancer when administered alone or in combination with chemotherapy. When to start therapy, the duration of treatment, adjuvant chemotherapy regimens and cardiotoxicity issues are examined.