DISEASE CHARACTERISTICS:

• Histologically confirmed prostate cancer

  • T2-3, N0, M0
  • No metastatic disease

• High-risk for PSA relapse as defined by Gleason score 7 or higher and ≥ 1 of the following OR Gleason score < 7 and ≥ 2 of the following:

  • Preoperative PSA > 10 ng/mL
  • Positive surgical margins
  • Seminal vesicle invasion
• Preoperative PSA ≤ 40.0 ng/mL
• Postoperative PSA ≤ 0.2 ng/mL

• Negative lymph node status by lymph node sampling or dissection

  • If lymph node status is unknown, must have < 5% risk of involvement by Roach formula

PATIENT CHARACTERISTICS:

Age:

• Not specified

Performance status:

• Zubrod 0-1

Life expectancy:

• Not specified

Hematopoietic:

• WBC ≥ 3,000/mm^3
• Platelet count ≥ 130,000/mm^3
• Hemoglobin ≥ 11.4 g/dL

Hepatic:

• ALT ≤ 3 times normal

Renal:

• Creatinine ≤ 2.5 mg/dL

Other:

• No other prior or concurrent invasive malignancy within the past 5 years except superficial nonmelanoma skin cancer
• No other major medical or psychiatric illness that would preclude study compliance

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• Not specified

Chemotherapy:

• At least 5 years since prior chemotherapy

Endocrine therapy:

• At least 60 days since prior finasteride
• At least 90 days since prior testosterone
• Prior pharmacologic androgen ablation for prostate cancer allowed if initiated within the past 10 months (must switch to study ablation therapy OR discontinue therapy if randomized to receive radiotherapy only)

Radiotherapy:

• No prior radiotherapy to the pelvis
• No concurrent intensity-modulated radiotherapy

Surgery:

• No prior orchiectomy