PURPOSE: Recent evidence suggests that reaching the lowest achievable levels of testosterone with androgen deprivation therapy delays disease progression and increases overall survival in men with advanced prostate cancer. The aim of this analysis was to compare posttreatment serum testosterone levels between patients undergoing subcapsular orchiectomy and patients treated with the luteinizing hormone-releasing hormone agonist triptorelin.

MATERIALS AND METHODS: In this randomized clinical trial we included 58 consecutive hormone naïve men diagnosed with advanced prostate cancer at Herlev and Gentofte University Hospital, Herlev, Denmark from September 2013 to March 2015. Followup was 48 weeks. Participants were randomly assigned 1:1 to subcapsular orchiectomy or triptorelin 22.5 mg given as 24-week depot injections. Androgen status was measured by liquid chromatography-tandem mass spectrometry prior to treatment and after 12, 24 and 48 weeks. Between group differences in achieved hormone levels were analyzed by longitudinal Tobit regression.

RESULTS: Triptorelin injections resulted in 29% lower testosterone levels (95% CI 17.2-41.7) compared to subcapsular orchiectomy (p <0.001). A significantly higher proportion of men receiving triptorelin had testosterone levels less than 20 ng/dl at 12 and 48 weeks compared to men undergoing orchiectomy (97% vs 79% and 100% vs 87%, respectively, p <0.05). There was no detectable difference in the adrenal androgen reduction between the treatment groups.

CONCLUSIONS: The use of 24-week depot triptorelin injections results in significantly lower testosterone levels compared to subcapsular orchiectomy. To our knowledge this is the first randomized study to demonstrate a difference in treatment effect between surgical and medical castration on testosterone levels.