OUTLINE: This is a dose escalation study. Patients are stratified according to 1 of the following 3 prognostic groups: Group 1: T1b-c or T2a-b with combined PSA/Gleason (CPG) score 15 and under Group 2: T1b-c or T2a-b with CPG score more than 15, or any T2c with PSA less than 70 ng/mL Group 3: T3 with prostate specific antigen (PSA) less than 70 ng/mL Patients receive 3-dimensional (3-D) conformal radiotherapy 5 days a week for 7.6, 8.2, or 8.8 weeks. Cohorts of 120-270 patients receive escalating doses of 3-D conformal radiotherapy until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 20% of patients experience dose-limiting toxicity. Patients are followed every 3 months for 1 year, every 4 months for 1 year, every 6 months for 3 years, and then annually thereafter.