Trastuzumab: new indication. Metastatic breast cancer, in combination with docetaxel: promising, but more evaluation is needed.

(1) There is no consensus on the optimal chemotherapy for metastatic breast cancer. Patients who have never previously received chemotherapy are generally given an anthracycline-based combination of cytotoxic agents. Options for patients who have already received an anthracycline include a taxane such as paclitaxel or docetaxel. The median survival time with these treatments is only about 2 to 2.5 years. (2) Trastuzumab is a monoclonal antibody directed against HER-2, a protein overexpressed by certain tumours, including about 25% of breast tumours. In 2000, the approved indications included first-line treatment of metastatic breast cancer in combination with paclitaxel. One clinical trial had shown, albeit with a low level of evidence, a median increase in survival of about 4 to 5 months. Trastuzumab is now approved for first-line treatment of metastatic breast cancer, in combination with docetaxel. (3) Evaluation data include the results of an open-label trial comparing docetaxel + trastuzumab with docetaxel monotherapy in 186 patients. The median survival time was significantly longer with the combination (31.2 versus 22.7 months). There are no relevant comparisons with other widely used cytotoxic drugs. Indirect comparison suggests that survival is similar with docetaxel + trastuzumab and paclitaxel + trastuzumab. (4) Data on the trastuzumab-docetaxel combination confirm the known adverse effects of trastuzumab, which include heart failure and diarrhea. Trastuzumab increases the frequency of docetaxel-induced neutropenia, which carries a risk of infections. (5) In summary, the results of clinical trials show that median survival time is increased by a few months when trastuzumab is added to a cytotoxic drug. However, the best cytotoxic agent is not known, and adverse effects are poorly documented. (6) In practice, trastuzumab has only been shown to benefit a minority of women with breast cancer, namely those whose tumours overexpress HER-2. Trastuzumab therapy is an option for metastatic breast cancer treatment, provided patients are enrolled in studies designed to answer the many outstanding questions.