A phase III randomized trial comparing intermittent versus continuous androgen suppression for patients with PSA progression after radical therapy: NCIC CTG PR.7/SWOG JPR.7/CTSU JPR.7/UK Intercontinental Trial CRUKE/01/013.

Abstract

3 Background: In men with PSA recurrence after radical radiotherapy (RRT), intermittent androgen suppression (IAS) has been suggested by phase II trials to improve quality of life (QoL) but effects on survival are unknown. In this Intergroup randomized phase III trial, we compared IAS vs continuous androgen deprivation (CAD) to test for non-inferiority of IAS with respect to overall survival (OS). Methods: Eligible men had rising PSA > 3.0 ng/ml >1 year post RRT, either initial or salvage, for localized prostate cancer. Patients could receive up to 1 year of neo/adjuvant androgen deprivation therapy (ADT) completed >1 year prior. Stratification factors were time since RRT (>1-3 vs >3 years), initial PSA (<15 vs >15), prior radical prostatectomy and prior ADT. IAS was delivered for 8 months in each cycle with restart when PSA reached >10 ng/ml off treatment. Primary endpoint was OS; secondary endpoints included time to hormone refractory state (HR), QoL, cholesterol/HDL/LDL, duration of treatment/non-treatment intervals, time to testosterone and potency recovery. The independent DSMC recommended halting the trial after a planned interim analysis demonstrated that a pre-specified stopping boundary for non-inferiority was crossed. Results: 1,386 patients were randomized to IAS (690) or CAD (696) arms. Arms were balanced for important baseline factors. Median follow up was 6.9 years. IAS patients completed a median of 2 x 8 month cycles (range: 1-9). 524 deaths were observed (268 on IAS vs 256 on CAD). Median OS was 8.8 vs 9.1 years on IAS and CAD arms, respectively (HR 1.02, 95%CI 0.86-1.21; p for non-inferiority [HR IAS vs CAD ≥ 1.25] = 0.009). The IAS arm had more disease related (122 vs 97) and fewer unrelated (134 vs 146) deaths. Time to HR was statistically significantly improved on the IAS arm (HR 0.80, 95%CI 0.67-0.98; p = 0.024). IAS patients had reduced hot flashes, but otherwise there was no evidence of differences in AEs, including myocardial events or osteoporotic fractures. Conclusions: In men with PSA recurrence after RRT IAS, given as described herein, is non-inferior to CAD with respect to OS. No significant financial relationships to disclose.