Patients with locally confined prostate adenocarcinoma (clinical stage T1c - T2bN0M0, Gleason score 7, PSA 20 ng/ml) are assigned to one of two treatment arms. Low risk patients (T1c-T2a and PSA <10 ng/ml and Gleason Score 6 or less) will receive 5 fractions of 8.0 Gy for a total of 40 Gy. Intermediate risk patients (T2b or PSA >10 ng/ml orGleason Score 7) will receive 1.8 Gy of IMRT for 25 fractions over 5 weeks for a total of 45 Gy. They will then receive a boost consisting of 4, 5.5 Gy fractions after IMRT for a total of 22 Gy.

Patients with locally confined prostate adenocarcinoma (clinical stage T1c - T2bN0M0, Gleason score 7, PSA 20 ng/ml) are assigned to one of two treatment arms. Low risk patients (T1c-T2a and PSA <10 ng/ml and Gleason Score 6 or less) will receive 5 fractions of 8.0 Gy for a total of 40 Gy. Intermediate risk patients (T2b or PSA >10 ng/ml orGleason Score 7) will receive 1.8 Gy of IMRT for 25 fractions over 5 weeks for a total of 45 Gy. They will then receive a boost consisting of 4, 5.5 Gy fractions after IMRT for a total of 22 Gy. All patients will be assessed for toxicity at periodic time points following completion of treatment.

Inclusion Criteria:

• Histologically determined adenocarcinoma is required.
• All other histologies are excluded.
• Tissue for diagnosis must be obtained by transrectal ultrasound biopsy.
• Gleason scoring classification of the biopsy specimen is required and must be greater than or equal to 7.
• 2002 AJCC clinical cancer stage as determined by either urologist or radiation oncologist must be T1c - T2b, N0, M0.
• N0 stage may be assigned following either negative imaging or negative pathologic assessment.
• Prostate volume as assessed by TRUS must be less than 60 cc. 3.1.5.
• PSA must be less than 20 ng/ml. ,
• Age ≥ 18,
• IPSS voiding symptoms score must be less than 18,
• Study consent form must be signed by the patient.

Exclusion Criteria:

• Gleason score of 8 - 10,
• Clinical stage T3 - T4,
• Age ≤ 18,
• Any evidence of nodal (N1) or distant (M1) disease,
• Prostate volume as assessed by TRUS > 60 cc,
• PSA > 20 ng/ml,
• IPSS voiding symptoms score > 18,
• Prior TURP,
• Prior pelvic radiotherapy or chemotherapy,
• Prior prostatectomy,
• Prior cancer other than basal cell or squamous cell skin carcinoma unless free of disease for > 5 years,
• Current medical or psychiatric illness that may interfere with treatment completion and followup,
• Hip prosthesis,
• Unable or unwilling to give informed consent