RATIONALE: Imaging procedures such as MRI may improve the ability to determine the response of prostate tumors to therapy.

PURPOSE: Phase II trial to study MRI results in patients with prostate cancer that has been treated with radiation therapy plus androgen suppression therapy.

OBJECTIVES: I. Establish whether changes between baseline and 2-month post androgen suppression endorectal coil MRI results predict for biochemical control following radiotherapy with androgen suppression in patients with adenocarcinoma of the prostate.

OUTLINE: Patients undergo a baseline endorectal coil MRI, followed by total androgen suppression (TAS) with either leuprolide IM or subcutaneous goserelin once a month plus oral flutamide 3 times a day for 2 months. Patients then receive a second endorectal coil MRI, followed by 2 months of external-beam radiotherapy plus TAS. Patients may receive an additional 2 months of TAS at the discretion of the treating physician. Patients are followed every 6 months for 3 years, then yearly thereafter.

PROJECTED ACCRUAL: Approximately 180 patients (approximately 60 per year) will be accrued for this study over a 34 months.

DISEASE CHARACTERISTICS: Histologically confirmed adenocarcinoma of the prostate AJCC stage T1b-T4b, N0 or Nx, M0 Transrectal, transperineal, or transurethral biopsy required

PATIENT CHARACTERISTICS: Age: 30 and over Performance status: CALGB 0-2 Hematopoietic: Not specified Hepatic: Not specified Renal: Not specified Other: The following may increase the risk of protocol treatment: Serious intercurrent medical illness that might compromise patient safety Active acute infection requiring antibiotics Suppression therapy for chronic urinary tract infection allowed Uncontrolled or severe cardiovascular disease Psychiatric conditions that prevent compliance or informed consent

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: No prior chemotherapy for carcinoma of the prostate Endocrine therapy: No prior androgen deprivation therapy (medical or surgical) Radiotherapy: No prior radiation therapy for carcinoma of the prostate Surgery: No prior surgical androgen deprivation therapy