Node-Sparing Short-Course Radiation with CAPOX and Sintilimab for MSS Locally Advanced Colon Cancer: a Randomized, Prospective, Multicenter Study

"Radiotherapy Protocol:~Short-course radiotherapy using three-dimensional conformal or intensity-modulated radiation therapy techniques. The radiation field will be limited to the tumor bed of the primary colon lesion, excluding surrounding draining lymph nodes and enlarged lymph nodes. The dose is fractionated as 5Gy per fraction, for a total of 25Gy over 5 fractions. Titanium clips will be placed on the proximal and distal ends of the colonic lesion via colonoscopy to guide radiation therapy positioning.~Chemotherapy Protocol (CAPOX Regimen):~1. Oxaliplatin: 130 mg/m², administered intravenously (ivgtt), on day 1 (d1).~2. Capecitabine: 1000 mg/m², orally (po), twice daily (bid), from day 1 to day 14 (d1-14).~Immunotherapy Protocol:~During preoperative treatment, Sintilimab (immune checkpoint inhibitor) will be administered concurrently with each chemotherapy cycle."

Participants will receive 4 cycles of CAPOX chemotherapy followed by radical total mesorectal excision surgery, and then 4 additional cycles of postoperative CAPOX chemotherapy.