This study will ultimately aim to evaluate the side effects of treatment by asking 20 subjects to receive post-operative radiotherapy for prostate cancer with the treatment plan adapted after the first week of treatment to account for changes in the target shape. These patients will be asked to complete toxicity scores and a quality of life questionnaire at the start and completion of treatment, and at 3 months 1, 2 and 5 years from the start of radiotherapy. These results will be used to determine the feasibility of the proposed approach, and obtain early estimates of improvements in uncertainty margin requirements for this population of patients.

Inclusion Criteria:

• Histologic diagnosis of adenocarcinoma of the prostate after radical prostatectomy AND
• Clinical stage pT3, pT4, or pT2 with positive margin OR
• Any p-Stage with a persistently elevated post-operative PSA > 0.05 ng/ml OR
• A delayed rise in PSA post-operatively

Exclusion Criteria:

• Inflammatory bowel disease or other contraindications to radiotherapy
• Prior pelvic radiotherapy
• Previous cytotoxic chemotherapy
• Radiological or pathologic evidence of nodal metastases.
• Planned radiotherapy to pelvic lymph nodes
• Evidence of systemic metastases on imaging.
• Prosthetic hip replacement
• No signed informed consent