Detailed analysis of a randomized phase III trial: can the tolerability of capecitabine plus docetaxel be improved without compromising its survival advantage?

Background: In a phase III trial, 3-weekly capecitabine (1250 mg/m(2) twice daily days 1-14) plus docetaxel (75 mg/m(2) day 1) demonstrated significantly superior overall survival to 3-weekly docetaxel (100 mg/m(2) day 1). We report a retrospective analysis of the impact of capecitabine/docetaxel dose reduction on safety and efficacy. Patients and methods: Safety and efficacy data were analyzed retrospectively according to the actual doses of capecitabine and docetaxel administered. Results: More patients receiving capecitabine/docetaxel (65%) had dose reductions for adverse events than docetaxel alone (35%). In most patients requiring dose reduction with the combination (80%), capecitabine and docetaxel were simultaneously reduced to 950 mg/m(2) and 55 mg/m(2), respectively. Subsequently, there were fewer cycles (17%) with grade 3/4 adverse events than with the full doses (34%). Time to progression and overall survival appeared to be similar in patients starting the second cycle with reduced doses of capecitabine/docetaxel and those who continued to receive full doses of capecitabine/docetaxel for at least the first four cycles. Conclusions: Capecitabine/docetaxel dosing flexibility allows management of side-effects without compromising efficacy. This retrospective analysis, as well as multiple phase II studies of taxanes with reduced-dose capecitabine, shows that reducing the starting dose of capecitabine with docetaxel is a reasonable strategy for the treatment of patients with metastatic breast cancer. In addition, reducing the dose of both agents may be appropriate.