Purpose: We conducted a randomized trial to compare intermittent and continuous androgen deprivation in patients with advanced prostate cancer. We studied time to progression, overall and prostate cancer specific survival, and time to treatment failure.

Materials and methods: Between May 1997 and February 2003, 852 men with locally advanced or metastatic prostate cancer were enrolled to receive androgen deprivation therapy for 24 weeks. Patients in whom prostate specific antigen decreased to less than 10 ng/ml, or by 50% or more if less than 20 ng/ml at baseline, were randomized to intermittent or continuous androgen deprivation. In the intermittent therapy arm androgen deprivation therapy was withdrawn and resumed again for at least 24 weeks based mainly on prostate specific antigen decrease and increase.

Results: There were 298 patients who did not meet the randomization criteria. The remaining 554 patients were randomized, with 274 (49.5%) to intermittent androgen deprivation and 280 (50.5%) to the continuous androgen deprivation arm. Median followup was 65.0 months. Of these patients 392 (71%) died, including 186 (68%) in the intermittent androgen deprivation arm and 206 (74%) in the continuous androgen deprivation arm (p=0.12). There were 248 prostate cancer deaths, comprised of 117 (43%) in the intermittent androgen deprivation and 131 (47%) in the continuous androgen deprivation arm (p=0.29). Median times from randomization to progression were 34.5 and 30.2 months in the intermittent androgen deprivation and continuous androgen deprivation arms, respectively. Median times to death (all cause) were 45.2 and 45.7 months, to prostate cancer death 45.2 and 44.3 months, and to treatment failure 29.9 and 30.5 months, respectively.

Conclusions: Intermittent androgen deprivation is a feasible, efficient and safe method to treat advanced prostate cancer compared with continuous androgen deprivation.