Inclusion Criteria:

Eligibility is not restricted to MSKCC to confirm biopsy/diagnosis. Participating
institution testing is sufficient.

- Low and intermediate risk prostate cancer patients will be eligible for this study.
Risk groups will be assigned as per NCCN guidelines.

- Low risk patients will be defined as:

- PSA < or = to 10 ng/ml and

- Gleason score = 6 and

- Clinical Stage < or = to T2a

- Intermediate risk patients will be defined as:

- PSA 10-20 ng/ml or

- Gleason score = 7 or

- Clinical stage T2b/T2c

Additionally, patients will be required to meet the following criteria:

- Age > or = to 18

- KPS > or = to 70

- Pre-treatment endorectal coil MRI or CT (MRI preferred) at MSKCC showing no definite
evidence of radiographic T3, T4, or N1 disease

- Prostate size < or = to 60 cc

- International Prostate Symptom Score < or = to 15

Exclusion Criteria:

- Prior androgen deprivation therapy for prostate cancer

- Elective pelvic lymph node irradiation

- KPS < 70

- Endorectal coil MRI or CT (MRI preferred) evidence of radiographic T3, T4 or N1
disease

- Presence of distant metastasis as determined by:

o alkaline phosphatase < LLN or

- whole body bone scan negative for osseous metastases

- Prior history of transurethral resection of the prostate

- Prior history of chronic prostatitis

- Prior history of urethral stricture

- Prior history of pelvic irradiation

- History of inflammatory bowel disease

- Unable to give informed consent

- Unable to complete quality of life questionnaires Abnormal complete blood count.
Any of the following

- Platelet count less than 75,000/ml

- Hb level less than 10 gm/dl

- WBC less than 3.5/ml

- Abnormal renal function tests (creatinine > 1.5)