Radiation therapy is one of the standard treatments for men with prostate cancer who have detectable levels of prostate specific antigen (PSA, a prostate cancer specific marker) after surgery. When radiation therapy is given to patients who have an increase in PSA after surgery, it is called "salvage radiation therapy". Currently the standard radiation therapy course length for this type of cancer is around 7 ½ -8 weeks. Sometimes, radiation therapy after prostate removal causes unpleasant side effects. A shorter course of radiation therapy, known as a "hypofractionated" course, gives fewer but higher doses of radiation than standard radiation.

The purpose of this study is to test the safety of a shorter course of radiation therapy at progressively lower dose levels and shorter lengths of treatment (hypofractionated) with patients who have had their prostate removed. The study will assess whether the hypofractionated course works better without causing additional side effects to the remaining cancer cells in the prostate bed.

Primary Objectives:

To determine the shortest dose-fractionation schedule (Dose Schedule) with acceptable grade ¡Ã 3 GU/GI toxicity rate for salvage HypoFx RT to maintain a constant, high BED for prostate cancer response while reducing the BED for late GU and GI toxicity

To assess health-related quality of life (HRQOL) of the recommended Dose Schedule of salvage HypoFx RT by demonstrating no significant change in 1-year disease specific QoL, as compared to baseline

Secondary Objectives:

To evaluate and characterize the acute and late genitourinary (GU) and gastrointestinal (GI) adverse effects associated with postoperative, hypofractionated radiation therapy.

To evaluate biochemical failure rate, defined separately as nadir plus 2 ng/mL and as three consecutive rises in PSA, at 2 years after hypofractionated, post-prostatectomy radiation therapy.

To evaluate health utilities at 1 year after HypoFx salvage RT, as measured by the EQ-5D instrument.

To evaluate changes in sexual domain of EPIC quality of life instrument at 1 year after HypoFx salvage RT.

To evaluate the treatment burden for patients undergoing salvage HypoFx RT, in order to examine whether HypoFx RT results in less burdensome treatment for patients, as measured by patient-reported direct and indirect (i.e., transportation) health care costs and lost productivity due to treatment, as evaluated by the Work Productivity and Activity Impairment Questionnaire¢-General Health (WPAI-GH).

Inclusion Criteria:

• diagnosis of prostate adenocarcinoma and
• have had a prostatectomy
• have detectable PSA
• 18 years of age or older

Exclusion Criteria:

• are receiving chemotherapy or other agents intended for cancer treatment
• history of rectal surgery or lower gastrointestinal bleed
• history of bleeding diathesis or abnormal sensitivity to ionizing radiation
• had prior pelvic irradiation or are scheduled to receive pelvic nodal irradiation