The international experience with docetaxel in the treatment of breast cancer.

The extensively studied agent docetaxel (Taxotere) has shown marked clinical activity in the treatment of anthracycline-resistant breast cancer. Phase I trials indicate that toxicities, such as mucositis and neutropenia, limit the administration of docetaxel to shorter perfusion schedules. Pharmacokinetic studies have shown that docetaxel's clearance by hepatic metabolism is correlated with a marked increase in risk of toxicity in patients with impaired liver function. Nevertheless, studies of docetaxel as front-line therapy for breast cancer were initiated because of its good activity against tumors in early studies and its close relationship to paclitaxel (Taxol), an agent with proven efficacy. Phase II studies have demonstrated excellent activity for docetaxel as a single agent, with an overall response rate of 61% in trials of a 100-mg/m2 dose. A phase III study is currently comparing docetaxel with paclitaxel as single-agent therapy. Docetaxel is expected to provide a better response rate but a higher incidence of neutropenia. The agent shows promise in adjuvant therapy, with very high response rates in anthracycline-resistant patients. Preliminary results of tests using docetaxel in combination with doxorubicin show high objective response rates but low complete response rates; early results suggest that this combination may have some advantages over paclitaxel/doxorubicin.