Interim report of a randomized trial comparing Zoladex 3.6 mg depot with diethylstilbestrol 3 mg/day in advanced prostate cancer. The West Midlands Urology Research Group.

A study comparing Zoladex 3.6 mg depot with diethylstilbestrol (DES) 3 mg/day was initiated in August 1985. One hundred ninety-three patients with histologically confirmed prostate cancer T3/4 or M1 have been randomized up to 31 March 1987: 95 to Zoladex, 98 to DES. No patient had received prior systemic therapy. There is no bias in the treatment groups in terms of baseline characteristics. Median follow-up is 11 months, and the response rate at 12 months from randomization (CR + PR) for Zoladex is 70 +/- 9.4% and 50 +/- 10.1% for DES. Median time to best response is 6 months for Zoladex and 12 months for DES (using the Kaplan-Meier life table method). Subjective responses are 56 +/- 10.2% for Zoladex and 44 +/- 10% for DES. Five increases in bone pain were found after the first Zoladex treatment, as well as one increased ureteric obstruction. None required treatment withdrawal. Seventeen patients on DES were withdrawn due to adverse reaction (chi 2 = 4.33, 1df, p less than 0.05). Overall survival at 31 March 1987 is 84% for the Zoladex group and 78% for the DES group. This study has shown that Zoladex is superior to DES in achieving early tumor response in advanced prostate cancer, without causing serious complications warranting withdrawal of treatment.