Updated results of the phase III Radiation Therapy Oncology Group (RTOG) trial 85-31 evaluating the potential benefit of androgen suppression following standard radiation therapy for unfavorable prognosis carcinoma of the prostate

PURPOSE: To determine the potential advantage of androgen ablation following standard external-beam radiation therapy in patients with locally advanced (clinical or pathologic T3; clinical or pathologic node positive) carcinoma of the prostate. METHODS AND MATERIALS: In 1987 the RTOG initiated a Phase III trial of long-term adjuvant goserelin in definitively irradiated patients with carcinoma of the prostate. A total of 977 patients were accrued to the study of which 945 remain analyzable: 477 on the adjuvant hormone arm (Arm I); and 468 on the radiation only arm (Arm II) with hormones initiated at relapse. The initial results were reported in the Journal of Clinical Oncology in 1997. RESULTS: With a median follow up of 5.6 years for all patients and 6.0 years for living patients local failure at 8 years was 23% for Arm I and 37% for Arm II (p < 0.0001). Distant metastasis was likewise favorably impacted with the immediate use of hormonal manipulation with a distant metastasis rate in Arm I of 27% and 37% in Arm II (p < 0.0001). Disease-free survival (NED survival) and NED survival with PSA of 1.5 ng/mL (bNED) or less were both statistically significant in favor of the immediate hormone arm (both p < 0.0001). Cause-specific failure was not statistically different with a cause-specific failure of 16% for Arm I and 21% in Arm II (p = 0.23). Overall survival was likewise not statistically different between two arms, with a 49% overall survival at 8 years in Arm I and 47% in Arm II (p = 0.36). Subset analysis of centrally reviewed Gleason 8-10 patients who did not undergo prostatectomy showed that for patients receiving radiation therapy plus adjuvant hormones there was a statistically significant improvement in both absolute (p = 0.036) and cause-specific survival (p = 0.019). CONCLUSIONS: Use of long-term adjuvant androgen deprivation in addition to definitive radiation therapy results in a highly significant improvement in regards to local control, freedom from distant metastasis, and biochemical free survival in unfavorable prognosis patients with carcinoma of the prostate.