Duration of Testosterone Suppression after a 9.45 mg Implant of the GnRH-Analogue Buserelin in Patients with Localised Carcinoma of the Prostate: A 12-Month Follow-up Study

Objectives(1) To determine the duration of androgen deprivation after a single buserelin implant 9.45 mg in the neoadjuvant setting in combination with curative radiation therapy of carcinoma of the prostate, and (2) to evaluate the time to recovery of gonadal function, and the incidence and duration of hypogonadal symptoms.MethodsWe prospectively evaluated 21 men with carcinoma of the prostate who received one implant of 9.45 mg buserelin subcutaneously. Release of buserelin, changes in serum testosterone concentration, hot flushing and sexual function over a 12-month study period were recorded.ResultsTestosterone was suppressed below the castration limit (0.58 ng/ml = 2 nmol/l) for 224 days (range, 139–309). The mean time to first return of testosterone above the castration limit was 246 days (range, 168–344); 50% of pre-treatment value was reached after 285 days (range, 218–370). The prevalence of hot flushing was 19 of 21 patients (90%) at 12 weeks. At the end of the study period, serum testosterone had reached 80% (range, 33%–166%) of pre-treatment concentration, sexual interest was present in 52%, erection was possible in 60%, and hot flushing remained in 24%.ConclusionA single injection of 3-month buserelin implant 9.45 mg suppresses serum testosterone below the castration limit for at least 6 months. Testosterone secretion recovers by 8–12 months. Hypogonadal symptoms decreased with the restoration of serum testosterone secretion. These data are clinically relevant regarding the dose schedule for buserelin and the patient information provided.