RATIONALE: Radiation therapy uses high-energy x-rays to kill tumor cells. Androgens can cause the growth of prostate cancer cells. Antihormone therapy, such as goserelin, may stop the adrenal glands from making androgens. Giving radiation therapy with or without goserelin after surgery may kill any tumor cells that remain after surgery. It is not yet known whether radiation therapy is more effective with or without goserelin in treating prostate cancer.

PURPOSE: This randomized phase III trial is studying radiation therapy and goserelin to see how well they work compared with radiation therapy alone in treating patients who have undergone surgery for recurrent or refractory prostate cancer.

OBJECTIVES:

Primary

• Compare the efficacy of adjuvant radiotherapy with vs without concurrent goserelin, in terms of biological and/or clinical progression-free survival, in patients who have undergone surgery for recurrent or refractory prostate cancer.

Secondary

• Compare overall survival of patients treated with these regimens.
• Compare metastases-free survival of patients treated with these regimens.
• Compare the immediate and delayed toxicities of these regimens.
• Compare the delay in reaching the prostate-specific antigen nadir in patients treated with these regimens.
• Compare the quality of life at 1 and 5 years after radiotherapy in these patients.
• Compare the functional dependence at 1 and 5 years after radiotherapy in patients age 75 years and over.

OUTLINE: This is an open-label, randomized, parallel-group, multicenter study. Patients are randomized to 1 of 2 treatment arms.

• Arm I: Patients undergo radiotherapy once daily, 5 days a week, for 7 weeks.
• Arm II: Patients undergo radiotherapy as in arm I. Patients also receive goserelin subcutaneously on day 1 and again 3 months later.

Quality of life is assessed periodically.

After completion of study therapy, patients are followed periodically for 10 years.

PROJECTED ACCRUAL: A total of 466 patients will be accrued for this study.

DISEASE CHARACTERISTICS:

• Histologically confirmed adenocarcinoma of the prostate

  • Localized disease treated with surgery only
  • pT2, pT3, or pT4
  • pN0 or pNx
  • No clinical signs of progressive disease

• Prostate-specific antigen (PSA) meeting the following criteria:

  • PSA ≤ 0.1 ng/mL after prostatectomy
  • PSA ≥ 0.2 ng/mL and < 2 ng/mL at study entry

PATIENT CHARACTERISTICS:

• ECOG performance status 0-1
• Life expectancy ≥ 10 years
• No other cancer in the past 5 years except for treated basal cell skin cancer
• No known pituitary gland adenoma
• No uncontrolled hypertension (i.e., blood pressure ≥ 160 mm Hg systolic and/or 90 mm Hg diastolic)
• No geographical, social, or psychological condition that would preclude study treatment

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics
• No prior hormonal therapy
• No prior pelvic radiotherapy
• No prior surgical or chemical castration
• At least 6 months since surgery for biological recurrence
• No other concurrent anticancer therapy