Oral estramustine phosphate and oral etoposide for the treatment of hormone‐refractory prostate cancer

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Abstract
Background : The purpose of the present study was to evaluate the antitumor activity and toxicity of oral estramustine phosphate (EMP) in combination with oral etoposide in patients with hormone‐refractory prostate cancer. Methods : Twenty patients with adenocarcinoma of the prostate that progressed after one or more regimens of androgen‐deprivation therapy were enrolled into this trial. Oral EMP was administered twice daily, for a total daily dose of 560 mg, and oral etoposide (50 mg/bodyweight per day) was given on days 1–21 and was stopped on days 22–35. Treatment was continued until evidence of disease progression appeared or two consecutive rises in the prostate‐specific antigen (PSA) value were observed. Results : Ten of 20 patients showed a decrease of 50% or greater in the PSA value from initially elevated PSA levels after therapy. The median progression‐free duration and 2 year cause‐specific survival rate of these 10 patients were 208 days (range 71–693 days) and 67.5%, respectively. There were no significant differences in age, pretreatment PSA value, duration from initial treatment to relapse, prior therapy or survival between patients who had a decrease of 50% or greater in PSA values after this combination therapy and those who did not. The main toxicities (≥ grade 2) were anemia, leukocytopenia, thrombocytopenia, gastrointestinal and hepatic disorders, which occurred in 40, 15, 10, 15 and 5% of patients, respectively. Conclusions : The combination of oral EMP and etoposide is considered to be a well‐tolerated outpatient treatment regimen for patients with hormone‐refractory prostate cancer and the therapy deserves further investigation.