Intergroup trial shows that intermittent androgen suppression is non-inferior to continuous androgen deprivation in men with PSA recurrence after radical therapy
Eligible men had rising PSA > 3.0 ng/ml more than one year after radical radiotherapy, either initial or salvage, for localized prostate cancer. Patients could receive up to 1 year of neo/adjuvant androgen deprivation therapy. Stratification factors were time since radical radiotherapy, initial PSA, prior radical prostatectomy and prior androgen deprivation therapy. Intermittent androgen suppression was delivered for 8 months in each cycle with restart when PSA reached >10 ng/ml off treatment. Primary endpoint was overall survival; secondary endpoints included time to hormone refractory state, QoL, cholesterol/HDL/LDL, duration of treatment/non-treatment intervals, time to testosterone and potency recovery. The independent Data and Safety Monitoring Committee recommended halting the trial after a planned interim analysis demonstrated that a pre-specified stopping boundary for non-inferiority was crossed.
Investigators randomized 1,386 patients, 690 to intermittent and 696 to continuous androgen deprivation. Arms were balanced for important baseline factors. Median follow up was 6.9 years. Intermittent androgen suppression patients completed a median of 2 x 8 month cycles. A total of 524 deaths were observed (268 on intermittent vs 256 on continuous androgen deprivation). Median overall survival was 8.8 vs 9.1 years on intermittent and continuous androgen deprivation arms, respectively (p=0.009). The intermittent androgen suppression arm had more disease related (122 vs 97) and fewer unrelated (134 vs 146) deaths. Time to the hormone refractory state was statistically significantly improved on the intermittent androgen suppression arm (p=0.024). Intermittent androgen suppression patients had reduced hot flashes, but otherwise there was no evidence of differences in adverse events, including myocardial events or osteoporotic fractures.
The authors, who presented results at the fourth annual Genitourinary Cancers Symposium (17-19 February 2011, Orlando, USA), concluded that in men with PSA recurrence after radical radiotherapy, intermittent androgen suppression, given as described herein, is non-inferior to continuous androgen deprivation with respect to the overall survival.
The Genitourinary Cancers Symposium was co-sponsored by the American Society of Clinical Oncology, the American Society for Radiation Oncology and the Society of Urologic Oncology.
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