Docetaxel administered every 3 weeks is a standard treatment for castration-resistant advanced prostate cancer. We hypothesised that 2-weekly administration of docetaxel would be better tolerated than 3-weekly docetaxel in patients with castration-resistant advanced prostate cancer, and did a prospective, multicentre, randomised, phase 3 study to compare efficacy and safety.

Eligible patients had advanced prostate cancer (metastasis, a prostate-specific-antigen test result of more than 10·0 ng/mL, and WHO performance status score of 0-2), had received no chemotherapy (except with estramustine), had undergone surgical or chemical castration, and had been referred to a treatment centre in Finland, Ireland, or Sweden. Enrolment and treatment were done between March 1, 2004, and May 31, 2009. Randomisation was done centrally and stratified by centre and WHO performance status score of 0-1 vs 2. Patients were assigned 75 mg/m(2) docetaxel intravenously on day 1 of a 3-week cycle, or 50 mg/m(2) docetaxel intravenously on days 1 and 15 of a 4-week cycle. 10 mg oral prednisolone was administered daily to all patients. The primary endpoint was time to treatment failure (TTTF). We assessed data in the per-protocol population. This study is registered with ClinicalTrials.gov, number NCT00255606.

177 patients were randomly assigned to the 2-weekly docetaxel group and 184 to the 3-weekly group. 170 patients in the 2-weekly group and 176 in the 3-weekly group were included in the analysis. The 2-weekly administration was associated with significantly longer TTTF than was 3-weekly administration (5·6 months, 95% CI 5·0-6·2 vs 4·9 months, 4·5-5·4; hazard ratio 1·3, 95% CI 1·1-1·6, p=0·014). Grade 3-4 adverse events occurred more frequently in the 3-weekly than in the 2-weekly administration group, including neutropenia (93 [53%] vs 61 [36%]), leucopenia (51 [29%] vs 22 [13%]), and febrile neutropenia (25 [14%] vs six [4%]). Neutropenic infections were reported more frequently in patients who received docetaxel every 3 weeks (43 [24%] vs 11 [6%], p=0·002).

Administration of docetaxel every 2 weeks seems to be well tolerated in patients with castration-resistant advanced prostate cancer and could be a useful option when 3-weekly single-dose administration is unlikely to be tolerated.

Sanofi.