Intensity-Modulated Radiation Therapy in Treating Patients With Localized Prostate Cancer

DISEASE CHARACTERISTICS:

* Histologically confirmed adenocarcinoma of the prostate, meeting the following criteria:

  * Clinical stage T1b-T3a, N0, M0
  * Locally confined disease
  * Previously untreated disease
* Prostate-specific antigen (PSA) ≤ 30 ng/mL
* Estimated risk of seminal vesicle involvement \< 30%

  * Estimated risk of seminal vesicle involvement is defined as PSA + (\[Gleason score - 6\] x 10) (i.e., if Gleason score ≤ 6, then PSA must be ≤ 30 ng/mL; if Gleason score = 7, then PSA must be \< 20 ng/mL; if Gleason score = 8, then PSA must be \< 10 ng/mL; if Gleason score = 9 or 10 patient is ineligible)

PATIENT CHARACTERISTICS:

* WHO performance status 0 or 1
* Life expectancy \> 10 years (5 years for patients with poorly differentiated cancers)
* WBC \> 4,000/mm\^3
* Hemoglobin \> 11g/dL
* Platelet count \> 100,000/mm\^3
* No other active malignancy within the past 5 years except basal cell carcinoma
* No hip prosthesis or fixation that would interfere with standard radiation beam configuration
* No comorbid conditions likely to impact on the advisability of radical radiotherapy (e.g., previous inflammatory bowel disease, previous colorectal surgery, significant bladder instability, or urinary incontinence)

PRIOR CONCURRENT THERAPY:

* No prior pelvic radiotherapy
* No prior radical prostatectomy
* No prior androgen-deprivation therapy
* No concurrent full anticoagulation therapy with warfarin or heparin