Determination of Assay Cut-Off for the RadTox Test in Prostate Cancer Patients to Predict GI Radiation Toxicity

Inclusion Criteria: * Men diagnosed with adenocarcinoma of the prostate who have not received previous treatment (defined as prostatectomy, transurethral resection of the prostate \[TURP\], radiation of the pelvis, and GreenLight Laser Therapy) except for short-term (≤6 months) Androgen Deprivation Therapy (ADT) according to National Comprehensive Cancer Network (NCCN) guidelines. * Candidate for definitive prostate radiotherapy (either IMRT or proton). * Patients to be treated with IMRT should have all radiation treatment planned with IMRT, whereas patients to be treated with protons should have all radiation treatment planned with protons (including pelvic nodes if treated). * Localized prostate cancer, as confirmed by staging with Prostate-Specific Antigen (PSA), biopsy, Gleason score, and clinical stage. * Nuclear medicine bone imaging is required for confirmation of the absence of overt metastatic disease in bones if any high-risk criteria are identified (clinical stage T3a or higher; or 1-4 cores of Gleason score 8 \[NCCN Grade Group 4\] or 4+5; or PSA ≥20 ng/mL). * Diagnosed with any of the NCCN initial groups (i.e., Very-Low-Risk, Low-Risk, Intermediate-Risk \[both Favorable and Non-Favorable Intermediate-Risk\]; High-Risk; or Very-High-Risk) (see Appendix III for NCCN classifications of various risk groups). For Very-High-Risk, subjects are to have negative prostate cancer specific PET/CT imaging for confirmation of being metastasis free. * The score for Question 16…