DISEASE CHARACTERISTICS:

• Histologically confirmed organ confined stage I or II (T1-T2c) prostate cancer treated with radical prostatectomy and bilateral pelvic lymph node dissection

  • Radical prostatectomy performed within 90 days of enrollment AND
  • PSA less than 0.1 ng/mL

• Must be at high risk of clinical or biochemical failure post-prostatectomy as defined by at least one of the following:

  • For patients with prior androgen ablation (up to 3 months):

    • Gleason score at least 8 on pretreatment biopsy OR
    • Seminal vesicle invasion OR
    • Pretreatment biopsy Gleason score at least 7 and extraprostatic extension with positive surgical margins in prostatectomy specimen

  • For patients without prior androgen ablation:

    • Gleason grade sum score at least 8 on radical prostatectomy specimen OR
    • Seminal vesicle invasion regardless of grade OR
    • Extraprostatic extension and positive surgical margins and Gleason sum at least 7
• No evidence of metastatic disease

PATIENT CHARACTERISTICS:

Age:

• Not specified

Performance status:

• Not specified

Life expectancy:

• Not specified

Hematopoietic:

• Not specified

Hepatic:

• Liver function tests less than 2 times normal

Renal:

• Not specified

Other:

• No contraindications to the use of LHRH agonists or antiandrogens
• No active secondary malignancy in the past 5 years except squamous or basal cell skin cancer
• No concurrent medical condition that would preclude participation in this study

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• Not specified

Chemotherapy:

• Not specified

Endocrine therapy:

• See Disease Characteristics

Radiotherapy:

• No prior radiotherapy for prostate cancer

Surgery:

• See Disease Characteristics