Prostate cancer is the most common malignancy in males, and radiotherapy is a commonly chosen treatment option for patients with localized disease. Technical innovations such as three-dimensional conformal radiotherapy (3D CRT) and intensity-modulated radiotherapy permit radiation dose escalation and possibly better disease outcomes, but escalated doses may be accompanied by long-term complications. This study will examine, for the first time, the independent contribution of a patient's own genetic makeup to the development of post-radiation complications, permitting the future development of predictive tests to avoid radiation injury. To do this, the investigators will examine gene markers and blood proteins in a series of approximately 100 prostate cancer survivors who have received three-dimensional conformal radiotherapy between 1996 and 2000 at the Cross Cancer Institute.