RATIONALE: Radiation therapy uses high-energy x-rays and other types of radiation to kill tumor cells. Specialized radiation therapy, such as intensity-modulated radiation therapy, that delivers a high dose of radiation directly to the tumor may kill more tumor cells and cause less damage to normal tissue.

PURPOSE: This clinical trial studies intensity-modulated external beam radiation therapy in treating patients with prostate cancer.

PRIMARY OBJECTIVES:

I. To demonstrate that patients can safely receive IMRT teletherapy using the proposed IMRT fractionation schedule without experiencing a treatment limiting toxicity.

SECONDARY OBJECTIVES:

I. To assess treatment efficacy through the surrogate measures of PSA nadir and biochemical failure-free survival.

OUTLINE: Patients undergo hypofractionated intensity modulated radiotherapy once daily, 5 days a week, for 6 weeks in the absence of disease progression or unacceptable toxicity. Patients with intermediate- and high-risk disease may also receive concurrent and adjuvant or long-term androgen deprivation therapy for up to 36 months. After completion of study treatment, patients are followed at 4-6 weeks, every 4 months for 3 years, every 6 months for 2 years, and then annually until year 5.

Inclusion Criteria:

• Patients with biopsy-proven adenocarcinoma of the prostate are eligible for protocol enrollment when the following criteria are met; patients must have low, intermediate or high-risk adenocarcinoma of the prostate, as defined by the National Comprehensive Cancer Network (NCCN) criteria
• A diagnostic CT scan of the abdomen and pelvis will be obtained to rule out regional disease (maximum of 60 days prior to registration) for high-risk patients only
• A bone scan showing no evidence of metastatic disease is also required for patients whose prostate-specific antigen (PSA) is greater than 20 ng/ml, Gleason's sum is greater than 7, or T-stage is greater than T2b
• Alkaline phosphatase within 1.5 x upper limit of normal (ULN) is required for all patients beginning hormone therapy
• AST within 1.5 x ULN is required for all patients beginning hormone therapy
• Bilirubin within 1.5 x ULN is required for all patients beginning hormone therapy
• Karnofsky Performance score >= 80
• Prior to registration, patients having received no more than three months treatment with anti-androgen, luteinizing hormone-releasing hormone (LHRH) agonist, or a combination of the two remain eligible for protocol treatment; the qualifying PSA for these patients will be the value recorded prior to the initiation of the hormone therapy

Exclusion Criteria:

• Patients with history of inflammatory bowel disease, or who require steroid or cytotoxic therapy for collagen vascular disease
• Patients with a history of cancer other than skin cancer within five years of the initiation of protocol treatment
• Patients with a history of pelvic irradiation for any reason