Node-sparing Short-Course Radiation Combined With CAPOX and Tislelizumab for MSS Rectal Cancer

This study tests a new treatment approach for low rectal cancer in patients who want to avoid a permanent colostomy (bowel bag). It combines short-course radiation with chemotherapy (CAPOX) and an immunotherapy drug called tislelizumab, given before surgery, in patients whose cancer is microsatellite stable (MSS) — a type that typically does not respond as well to immunotherapy alone. **You may be eligible if...** - You are 18–75 years old with low rectal cancer (tumor within 10 cm of the anal opening) at clinical stage T3–T4b - Your cancer has been confirmed as MSS or pMMR by genetic testing - You strongly wish to preserve the anus and avoid a permanent colostomy - You have not had any prior cancer treatment - You are in good general health (ECOG 0–1) **You may NOT be eligible if...** - You have had a previous cancer other than rectal cancer - Your cancer has spread to distant organs - Your cancer has spread to lymph nodes outside the rectum's surrounding fat - You have a bowel blockage, perforation, or bleeding requiring emergency surgery - You have had prior pelvic radiation Talk to your doctor to see if this trial is right for you.