Randomized trial comparing 2 external beam radiotherapy fractionation schemes in patients with localized high risk prostate cancer. Primary endpoint is acute toxicity.

Patients enrolled onto this study will be randomized to one of the following treatment arms:

• Standard fractionation: Using 2 sequential IMRT plans, the pelvic lymph nodes and prostate will initially be treated to 46 Gy in 23 fractions, followed by a subsequent boost to the prostate to a total dose of 78 Gy.
• Hypofractionation: Using a one phase IMRT plan, the pelvic lymph nodes will be treated to a dose of 48 Gy in 25 fractions, while the prostate will be treated to a dose of 68 Gy in 25 fractions concomitantly (simulataneous integrated boost).

In addition, all patients receive 1.5- 3 years of androgen deprivation therapy.

Inclusion Criteria:

• Written informed consent obtained.
• Histologically confirmed diagnosis of adenocarcinoma of the prostate.
• T1-2 N0 M0, Gleason Score <= 7, PSA 20 - 100
• T1-2 N0 M0, Gleason Score 8 - 10, PSA <= 100
• T3 N0 M0, any Gleason Score, PSA <= 100

Exclusion Criteria:

• Patients with unilateral or bilateral hip replacement.
• Patients with active collagen vascular disease.
• Patients with active inflammatory bowel disease.
• Patients with previous radiotherapy to the pelvis.
• Patients with ataxia telangiectasia.
• Patients with nodal or distant metastases