Phase III trial of androgen suppression using goserelin in unfavorable-prognosis carcinoma of the prostate treated with definitive radiotherapy: report of Radiation Therapy Oncology Group Protocol 85-31.

Abstract

PURPOSE Although androgen suppression results in a tumor response/remission in the majority of patients with carcinoma of the prostate, its potential value as an adjuvant has not been substantiated. MATERIALS AND METHODS In 1987, the Radiation Therapy Oncology Group (RTOG) initiated a randomized phase III trial of adjuvant goserelin in definitively irradiated patients with carcinoma of the prostate. A total of 977 patients had been accessioned to the study. Of these, 945 remained analyzable: 477 on the adjuvant arm and 468 on the observation arm. RESULTS Actuarial projections show that at 5 years, 84% of patients on the adjuvant goserelin arm and 71% on the observation arm remain without evidence of local recurrence (P < .0001). The corresponding figures for freedom from distant metastases and disease-free survival are 83% versus 70% (P < .001) and 60% and 44% (P < .0001). If prostate-specific antigen (PSA) level greater than 1.5 ng is included as a failure (after > or = 1 year), the 5-year disease-free survival rate on the adjuvant goserelin arm is 53% versus 20% on the observation arm (P < .0001). The 5-year survival rate (for the entire population) is 75% on the adjuvant arm versus 71% on the observation arm (P = .52). However, in patients with centrally reviewed tumors with a Gleason score of 8 to 10, the difference in actuarial 5-year survival (66% on the adjuvant goserelin arm v 55% on the observation arm) reaches statistical significance (P = .03). CONCLUSION Application of androgen suppression as an adjuvant to definitive radiotherapy has been associated with a highly significant improvement in local control and freedom from disease progression. At this point, with a median follow-up time of 4.5 years, a significant improvement in survival has been observed only in patients with centrally reviewed tumors with a Gleason score of 8 to 10.