Node-sparing Radiotherapy Combined With Total Neoadjuvant CAPOX and Sintilimab for MSS Middle and Low Rectal Cancer

This trial tests a treatment approach for mid-to-low rectal cancer that aims to preserve the anus — combining targeted radiation, chemotherapy (CAPOX), and an immunotherapy drug (sintilimab) before surgery, to increase the chance of avoiding a permanent colostomy bag. **You may be eligible if...** - You have rectal cancer within 10 cm of the anal opening, confirmed by imaging and biopsy - Your tumor is locally advanced (stage T2-T4) but has not spread to distant organs - Your cancer is microsatellite stable (MSS) — a specific tumor type that is common - You have not received any prior cancer treatment - You are between 18 and 75 years old and in reasonably good health (ECOG 0–1) - You strongly want to preserve the anus and avoid a colostomy **You may NOT be eligible if...** - Your cancer has spread to organs outside the pelvis - You have received any prior chemotherapy, radiation, or immunotherapy - Your blood counts or organ function do not meet minimum levels - You have serious heart, liver, or immune conditions Talk to your doctor to see if this trial is right for you.