RATIONALE: Radiation therapy (RT) uses high-energy x-rays to damage tumor cells. Androgens can stimulate the growth of prostate cancer cells. Hormone therapy using flutamide, goserelin, and leuprolide may fight prostate cancer by reducing the production of androgens. It is not yet known which regimen of antiandrogen therapy is most effective for prostate cancer.

PURPOSE: Randomized phase III trial to study the effectiveness of radiation therapy with or without antiandrogen therapy in treating patients who have stage I or stage II prostate cancer.

OBJECTIVES: Primary: To evaluate whether a combination of Zoladex and flutamide used as cytoreductive agents prior to and during definitive radiation therapy improves overall survival over radiation therapy alone in locally confined carcinomas of the prostate; Secondary: To compare the rates of disease-specific survival, clinical relapse (local progression and/or distant failure), freedom from prostate-specific antigen (PSA) failure, freedom from second clinical relapse, freedom from second PSA relapse, and disease-free survival; To compare the prostate re-biopsy at two years; To measure the effect on sexual function.

OUTLINE: This is a randomized, multicenter study. Patients were stratified by PSA level (less than 4 vs 4-20), tumor differentiation (well vs moderate vs poor), nodal status (N0 [nodes evaluated by surgical sampling] vs NX [nodes evaluated negative by imaging methods only]), and participating center. Patients are randomized to one of two treatment arms. Arm I: Patients receive oral flutamide 3 times a day and goserelin subcutaneously once every 4 weeks, or once as a time release injection (intramuscular leuprolide may be substituted for goserelin), beginning 2 months prior to radiotherapy and continuing until completion of radiotherapy. Patients undergo radiotherapy daily 4-5 days per week for almost 8 weeks. Arm II: Patients undergo radiotherapy only, as in arm I. Patients are followed every 3 months for the remainder of the first year, every 4 months for the second year, every 6 months for the third through fifth years, and then annually thereafter.

PROJECTED ACCRUAL: A total of 1980 patients within 5 years.

Inclusion criteria:

• Histologically confirmed locally confined adenocarcinoma of the prostate with primary tumors confined to the prostate, clinical stage T1b,1c, 2a or 2b.
• Negative nodes evaluated by imaging methods (classified in the study as NX) or by surgical sampling (classified in the study as N0).
• Karnofsky performance status ≥ 70.
• PSA is mandatory, must be ≤ 20)
• No prior hormonal therapy, radiation or chemotherapy.
• Prior finasteride for prostate hypertrophy allowed if discontinued at least 60 days prior to randomization.
• Prior testosterone administration allowed if at least 90 days elapsed since last administration.
• No evidence of distant metastasis or other synchronous primary. Patients with prior invasive malignancy who were disease free for at least 5 years could be eligible with pre-randomization approval by the study chairman.
• Treatment begins within 21 days after randomization.
• Patients signs a study-specific informed consent form.
• Alanine Aminotransferase (ALT) within 2x upper normal limits.

Exclusion criteria:

• Stage T1a or ≥ T2c disease.
• Lymph node involvement (N1 - N3).
• Evidence of distant metastasis. (M1)
• PSA > 20.
• Radical surgery or cryosurgery for carcinoma of the prostate, previous irradiation, antiandrogen therapy or chemotherapy.
• Previous or concurrent cancers other than basal cell or squamous cell skin carcinoma.

Patients with squamous cell carcinomas required to be NED (no evidence of disease) for a minimum of two years prior to study entry.

• Major medical or psychiatric illness which, in the investigator's opinion, would prevent completion of treatment and would interfere with follow-up.
• Karnofsky performance status of < 70.