RATIONALE: Androgens can cause the growth of prostate cancer cells. Drugs, such as triptorelin and flutamide, may stop the adrenal glands from making androgens. Radiation therapy uses high-energy x-rays to kill tumor cells. Giving triptorelin and flutamide together with radiation therapy may be an effective treatment for prostate cancer. It is not yet known whether giving triptorelin and flutamide together with external-beam radiation therapy is more effective than external-beam radiation therapy alone in treating prostate cancer.

PURPOSE: This randomized phase III trial is studying triptorelin, flutamide, and external-beam radiation therapy to see how well they work compared to external-beam radiation therapy alone in treating patients with stage II or stage III prostate cancer.