Short-course Radiotherapy Combined With CAPOX and PD-1 Antibody Versus Long-course Chemoradiotherapy Combined With CAPOX for Early Low-lying Rectal Cancer

TORCH-E2 is a prospective, multicentre, randomized phase II trial. 134 low-lying early (T1-3b/N0-1M0, distance from anal verge ≤5cm) patients will be recruited and assigned to Group 1 and Group 2 (1:1). Group 1 receives SCRT (25Gy/5Fx) followed by 4 cycles of capecitabine plus oxaliplatin (CAPOX) chemotherapy and PD-1 antibody. Group 2 receives LCRT (50Gy/25Fx) followed by 2 cycles of CAPOX. A WW option can be applied to patients achieving cCR while surgery will be recommended for those who fail to achieve cCR. The primary endpoint is complete response (CR, pathological complete response \[pCR\] plus cCR) rate. The secondary endpoints include the grade 3-4 acute adverse effects (AE) rate, anal preservation rate, 3-year DFS rate, etc.