Taxanes for breast cancer: an evidence-based review of randomized phase II and phase III trials.

The taxanes paclitaxel and docetaxel have an important role in the treatment of breast cancer, and numerous randomized trials have evaluated their efficacy for this indication. A systematic, evidence-based review was performed, which included all randomized, controlled trials evaluating taxanes for the treatment of early-or advanced-stage breast cancer that were identified in CANCERLIT and MEDLINE searches. The primary objectives of this review were to determine the dose and schedule for each taxane that was associated with the most favorable therapeutic index, and to determine whether (and under what circumstances) the taxanes improved survival. The search revealed 18 randomized phase II (n = 1) or phase III (n = 17) trials. For metastatic breast cancer, the dose and schedule associated with the most favorable therapeutic index for paclitaxel was 175 mg/m2 given as a 3-hour infusion every 3 weeks, and docetaxel was 60-100 mg/m2 given as a 1-hour infusion every 3 weeks. Survival was improved under the following circumstances: (1) when 4 cycles of paclitaxel (175 mg/m2 every 3 weeks) was given following 4 cycles of conventional doxorubicin-cyclophosphamide for axillary node-positive operable breast cancer, (2) when trastuzumab was added to paclitaxel as first-line therapy for metastatic breast cancer that overexpressed HER2/neu, and (3) when docetaxel was given as second-line therapy for anthracycline-resistant disease. Although a survival benefit was found for taxanes as a component of first-line therapy in two of six trials, the interpretation of both positive trials was confounded by a lack of crossover to taxane therapy in those who were initially randomized to receive standard therapy. The taxanes improve survival in patients with early-stage breast cancer and selected patients with metastatic breast cancer. Further research is necessary in order to identify the efficacy of docetaxel relative to paclitaxel, the optimal dose of docetaxel, the role of weekly taxane therapy, the role of trastuzumab plus taxanes in early-stage disease, and whether taxanes are more effective when given concomitantly or sequentially in patients with early-stage disease.