Objective: To compare the effects of leuprolide acetate and goserelin acetate for suppressing serum testosterone levels in Japanese patients with prostate cancer, as several recent studies suggested that serum testosterone is not always suppressed below the upper limit of the castration range in patients using luteinizing hormone-releasing hormone (LH-RH) agonists, especially leuprolide acetate.
Patients and methods: In all, 232 patients with prostate cancer, whose serum testosterone levels were measured before and during treatment using a 1- or 3-monthly formulation of leuprolide or goserelin, were enrolled in a retrospective study. The mean age of the patients was 69.8 years and the mean testosterone level before the LHRH treatment was 4.54 ng/mL. The patients had their testosterone levels assessed a mean (range) of 5.4 (1-35) times during the LHRH treatment. A castrate serum testosterone level was defined as <or= 0.5 ng/mL.
Results: The mean maximum testosterone level during 1-monthly leuprolide (40 patients), 3-monthly leuprolide (68), 1-monthly goserelin (50), or 3-monthly goserelin (74) treatment was 0.22, 0.20, 0.19 and 0.20 ng/mL, respectively (not significant). Four patients, including two treated with 1-monthly leuprolide, one with 3-monthly leuprolide and one with 3-monthly goserelin, had serum testosterone above the castrate level, with a maximum of 0.5-0.65 ng/mL. Three of these patients had elevated testosterone only once or twice during the follow-up, and the remaining patient had serum testosterone fluctuating at 0.4-0.6 ng/mL throughout the follow-up.
Conclusions: One- and 3-monthly formulations of leuprolide and goserelin have equivalent and sufficient effects to suppress serum testosterone levels in men with prostate cancer. There were testosterone levels just outside the castrate range in a few patients during treatment.