Background: Intermittent androgen deprivation (IAD) for prostate cancer was studied with the objective of reducing the side effects of treatment and potentially delaying the development of hormone resistance. There also appears to be a quality of life benefit during off-treatment intervals owing to the recovery of serum testosterone levels.
Methods: In this multicentre European prospective randomised phase III trial EC507, testosterone serum concentrations were analysed in prostate cancer patients with PSA progression after radical prostatectomy. Patients were randomised to a continuous androgen deprivation (CAD) and IAD therapy using a 3-month depot with 11.25 mg leuprorelin acetate as microcapsule formulation. A complete IAD cycle comprises both a 6-month androgen deprivation therapy plus the off-treatment time (OTT).
Results: Serum testosterone recovery was recorded in 109 patients during OTT in the IAD group. Testosterone recovery to baseline values was achieved in 79.3% during the first and in 64.9% during the second IAD cycle, respectively. Median time to testosterone normalisation was 100 days in the first and 115 days in the second cycle, respectively. No significant difference was observed up to 1000 days between IAD and CAD with regard to time to androgen-independent progression. This is the first prospective study of leuprorelin acetate 11.25mg demonstrating normalisation of testosterone levels in the off-treatment period in patients undergoing IAD.
Conclusions: The prerequisite of an IAD treatment is the testosterone recovery during off-treatment periods. In this study, in patients with PSA relapse after radical prostatectomy, a real achievement of intermittent castration with normalisation of testosterone levels during off-treatment periods could be confirmed.