Intermittent versus continuous total androgen blockade in the treatment of patients with advanced hormone-naive prostate cancer: results of a prospective randomized multicenter trial.

The aim of this study was to compare the efficacy of total intermittent androgen deprivation (IAD) versus total continuous androgen deprivation (CAD) for treating patients with advanced prostate cancer in a phase III randomized trial. A total of 68 evaluable patients with hormone-naive advanced or relapsing prostate cancer were randomized to receive combined androgen blockade according to a continuous (n = 33) or intermittent (n = 35) regimen. Therapeutic monitoring was assessed by use of serum prostate-specific antigen (PSA) measurements. Patients in the CAD and IAD groups were equally stratified for age, biopsy Gleason score, and baseline serum PSA levels. The outcome variable was time to androgen-independence of the tumor, which was defined as increasing serum PSA levels despite androgen blockade. Mean follow-up was 30.8 months. The 35 IAD-treated patients completed 91 cycles, and 19 of them (54.3%) completed > or = 3 cycles. Median cycle length and percentage of time off therapy were 9.0 months and 59.5, respectively. The estimated 3-year progression rate was significantly lower in the IAD group (7.0% +/- 4.8%) than in the CAD group (38.9% +/- 11.2%, P = 0.0052). Our data suggest that IAD treatment may maintain the androgen-dependent state of advanced human prostate cancer, as assessed by PSA measurements, at least as long as CAD treatment. Further studies with longer follow-up times and larger patient cohorts are needed to determine the comparative impacts of CAD and IAD on survival.