Node-Sparing Short-Course Radiation Combined With Capecitabine and PD-1/CTLA-4 for MSS Early Rectal Cancer

Three-dimensional conformal or intensity-modulated radiotherapy targeting only the primary tumor bed (no regional lymph nodes), delivering a total dose of 25 Gy in 5 Gy fractions over five consecutive days.

Oral capecitabine 1,000 mg/m² administered twice daily on Days 1-14 of each 21-day cycle, for a total of four cycles.

Intravenous PD-1/CTLA-4 bispecific monoclonal antibody at 5 mg/kg every 3 weeks for four cycles, starting on Day 8 after completion of radiotherapy.