Determine of the optimal number of cycles of docetaxel in the treatment of metastatic castration-resistant prostate cancer.

To determine the optimal number of cycles of docetaxel for metastatic castration-resistant prostate cancer, we retrospectively collected 73 patients receiving varying numbers of docetaxel plus prednisolone and analyzed the clinical outcomes including overall survival, prostate-specific antigen (PSA) response, and adverse events. The study included 33 patients receiving ≤ 10 cycles of docetaxel and 40 patients receiving > 10 cycles. Patients receiving > 10 cycles were younger than those who received ≤ 10 cycles. There was no statistical significant difference in overall survival between the two groups (log-rank test, p = 0.75). Adverse effects were more common among patients receiving ≥ 10 cycles of treatment. A PSA flare-up was observed among six patients (8.2%); the median duration of the PSA surge was 3 weeks (range, 3-12 weeks). The overall survival rates in patients with PSA flare-up were comparable with the patients having PSA response. We concluded that at least four cycles of docetaxel should be administered in metastatic castration-resistant prostate cancer patients in order not to cease treatment prematurely from potentially beneficial chemotherapy. However, administering > 10 cycles does not result in any further improvement in survival and is associated with more adverse effects.