Adaptive Radiation Therapy (ART) Stereotactic Ablative Body Radiotherapy (SABR) for Primary Localized Prostate Cancer

This study tests a new type of radiation treatment for prostate cancer called adaptive stereotactic ablative body radiotherapy (SABR). Unlike standard radiation that uses many small doses over weeks, SABR delivers high-dose, very precise radiation in just a few sessions. The "adaptive" part means the treatment is adjusted based on how your body looks each day. Researchers want to see how well this approach controls the cancer while minimizing side effects. **You may be eligible if...** - You were assigned male at birth and are 18 or older - You have been diagnosed with prostate cancer (confirmed by biopsy) - Your cancer is classified as low to intermediate risk - You are in generally good health (able to care for yourself) - You are willing to attend follow-up visits **You may NOT be eligible if...** - Your cancer is very low, high, or very high risk - You have already had prostate cancer treatment (surgery, radiation, cryotherapy, or HIFU) - You've had a prostate procedure to relieve urinary blockage (e.g., TURP) - Your cancer has spread to other parts of the body - You have certain genetic conditions or inflammatory bowel disease - Your prostate is very large (over 80cc on MRI) or you have severe urinary symptoms - You weigh more than 200 kg - You are allergic to certain gel spacers (PEG) or iodine used during treatment Talk to your doctor to see if this trial is right for you.