Triptorelin and Radiation Therapy in Treating Patients Who Have Undergone Surgery for Intermediate-Risk Stage III or Stage IV Prostate Cancer

OBJECTIVES: Primary * Compare the efficacy, in terms of event-free survival at 5 years, of immediate radio-hormonal therapy immediately after prostatectomy for tumor pT2, R1, pN0, or pNx versus radio-hormonal therapy at biochemical relapse. Secondary * Compare the overall survival of patients treated with these regimens. * Compare the metastasis-free survival of these patients. * Compare the acute and late toxicities of these regimens in these patients. * Compare the quality of life of patients treated with these regimens. * Compare the functional dependence of patients over 75 years old. OUTLINE: Patients are randomized to 1 of 2 treatment arms. * Arm I (delayed treatment): Patients receive triptorelin intramuscularly on day 1 and then 3 months later. Patients also undergo conformal radiotherapy daily, 5 days a week, for 7 weeks. Treatment begins at biochemical relapse (PSA is more than 0.2 ng/mL) and before PSA is more than 2 ng/mL. * Arm II (immediate treatment): Patients receive treatment as in arm I, but treatment begins within 6 months after surgery. After completion of study treatment, patients are followed for up to 5 years.