Objective: To examine the efficacy and toxicity of a moderate dose (250 mg/day) of diethylstilbestrol diphosphate (DES-DP) intravenously administered to patients with hormone refractory prostate cancer (HRPC) as well as the influence of this agent on the endocrine system.
Patients and methods: Sixteen patients with HRPC were treated with a daily intravenous injection of 250 mg of DES-DP for 28 days. Eastern Cooperation Oncology Group (ECOG) performance status and pain score were used for subjective evaluation and PSA was used for objective evaluation. Testosterone, free testosterone, dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEA-S) were used for hormonal parameters.
Results: Fourteen patients were eligible. The mean patient age was 75.2 years. With respect to the ECOG pain score, 5 patients scored 1 or higher, in 4 patients, the pain completely disappeared, and in 1 patient, the pain score improved from 4 to 1. The PSA level decreased significantly from 528 +/- 556 ng/ml (mean +/- SD) to 154 +/- 197 ng/ml. The DHEA level was not changed during DES-DP administration. The DHEA-S level decreased significantly from 882 +/- 430 ng/ml to 480 +/- 236 ng/ml. Testosterone and free testosterone were in the castration level before and during the treatment. Toxicity was minimal. None of the patients developed cardiovascular disorder.
Conclusion: A moderate dose (250 mg/day) of DES-DP decreased PSA levels and relieved pain without causing serious toxicity in patients with HRPC. It is suggested that the mechanism of the DES-DP effect on the decrease in PSA and pain relief involves a decrease in DHEA-S.