Response to orchiectomy following Zoladex therapy for metastatic prostate carcinoma.

Serum testosterone and prostate-specific antigen (PSA) levels were measured in 3 patients with Stage D2 prostate cancer before and after discontinuation of the long-acting LHRH agonist, goserelin acetate (Zoladex). The patients had received goserelin acetate for ten, sixteen, and thirty months prior to discontinuing the drug because of progressive metastatic disease. In all 3 patients, PSA and testosterone levels increased after goserelin acetate was discontinued. In 2 patients the testosterone level reached normal levels. A bilateral orchiectomy was performed one hundred sixty, one hundred, and seven days, respectively, after the drug was discontinued. In all 3 cases PSA and testosterone levels were reduced following castration, although PSA levels again began to increase within two weeks of orchiectomy in 2 of the 3 patients. These findings suggest that suppression of testosterone by LHRH agonists is not permanent and if tumor progression occurs, maintaining hormone suppression may still be beneficial.