Short-course Radiotherapy or Long-course Chemoradiation Followed by MFOLFOXIRI Consolidation Chemotherapy for Organ Preservation in Low Rectal Cancer

This study is comparing two different approaches to treating rectal cancer — short-course radiation followed by intensive chemotherapy versus long-course chemoradiation followed by the same chemotherapy — with the goal of preserving the rectum and avoiding the need for a permanent colostomy bag. **You may be eligible if...** - You are 18–70 years old - You have been diagnosed with rectal cancer confirmed by biopsy (adenocarcinoma) - Your cancer is at an early to moderately advanced stage (cT2–4a, N0–2) - The lower edge of your tumor is within 8 cm of the anus - You have not had prior surgery, chemotherapy, or radiotherapy for your rectal cancer - Your cancer is pMMR-positive (a specific marker checked by biopsy) - Your general health is good (ECOG 0 or 1) and your blood counts and organ function are acceptable **You may NOT be eligible if...** - Your cancer has spread to distant parts of the body - Your tumor has a specific genetic marker (dMMR/MSI-H — your doctor can check this) - You have previously received treatment for rectal cancer - You have another active cancer - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.