Estramustine phosphate versus placebo as second line treatment after orchiectomy in patients with metastatic prostate cancer: DAPROCA study 9002. Danish Prostatic Cancer Group.

Purpose: We compared the effect of 560 mg. estramustine phosphate daily to placebo as a supplement to standard palliative therapy in patients with progressive disease after bilateral orchiectomy as first line therapy for metastatic prostate cancer.

Materials And Methods: In a double-blind multicenter study 131 patients with progressing metastatic hormone refractory prostate cancer were randomized to receive 280 mg. estramustine phosphate 2 times daily versus placebo. End points were clinical progression and death. Adverse events, decrease in prostate specific antigen (PSA) and subjective response were also assessed.

Results: Adverse events were common in both groups but breast tenderness/gynecomastia and diarrhea were more frequent among patients in the estramustine phosphate group. Subjective responses were few (9 of 50 estramustine phosphate and 4 of 57 placebo cases, p = 0.15). Median observation time for survival was 43 months and 124 patients died. Median time to subjective progression and median overall survival did not differ significantly between the 2 groups at 4.6 and 9.4 months in the estramustine phosphate group versus 5.0 and 6.1 months in the placebo group. Of 61 patients in the estramustine phosphate group 29 achieved a reduction in PSA of more than 25% at 1 month of followup compared to only 3 of 68 receiving placebo. A decrease in PSA after 1 month correlated significantly with survival.

Conclusions: Although this study did not prove estramustine phosphate to be superior to placebo in terms of protocol end points, it generates the hypothesis that prolonged survival may be achieved with estramustine phosphate treatment in a subgroup of patients and that this may be predicted by a decrease in PSA after 1 month of therapy.