Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed adenocarcinoma of the prostate

- Disease confirmed by biopsy within 1 year of study entry

- Gleason score 2-7(3+4)

- Clinical stage T1a or T2b, N0 or NX, M0 or MX

- T- stage and N-stage determined by physical exam and available imaging
studies (i.e., ultrasound, CT scan, and/or MRI)

- M-stage determined by physical exam, CT scan, and/or MRI

- Bone scan is not required unless clinical findings suggest possible
osseous metastases

- PSA ≤ 10 ng/mL within the past 60 days

- At risk for recurrence, as defined by 1 of the following risk groups:

- Low-risk, defined by the following combination:

- Stage T1a-T2a, Gleason 2-6, and PSA ≤ 10 ng/mL

- Low- to-Intermediate-risk, defined by either of the following combinations:

- Stage T2b, Gleason 2-6, and PSA ≤ 10 ng/mL

- Stage T2b, Gleason 3+4=7, and PSA ≤ 10 ng/mL

- Prostate volume must be ≤ 100 cc

- Determined by measurement from CT scan or ultrasound within the past 90 days or
within the past 14 days if hormone therapy is given

PATIENT CHARACTERISTICS:

- ECOG performance status 0-1

- No implanted hardware or other material that would prohibit appropriate treatment
planning or treatment delivery, in the investigator's opinion

PRIOR CONCURRENT THERAPY:

- No prior definitive therapy for prostate cancer, including prostatectomy,
cryotherapy, or radiotherapy to the prostate or lower pelvis

- No more than 6 months of hormone ablation for gland downsizing