A Series of Neoadjuvant Chemoradiotherapy Combined With Immunotherapy for Locally Advanced Rectal Cancer

The goal of this clinical trial is to compare the efficacy and safety of neoadjuvant chemoradiotherapy combined with tirelizumab compared with neoadjuvant chemoradiotherapy alone for neoadjuvant therapy in patients with locally advanced rectal cancer. The main questions it aims to answer are: To evaluate the efficacy and safety of neoadjuvant chemoradiotherapy combined with tirelizumab compared with neoadjuvant chemoradiotherapy alone for neoadjuvant therapy in patients with locally advanced rectal cancer To assess rectal or anal retention as well as quality of life. Participants will receive a long course of NCRT (50 Gy / 25f, capecitabine 850-1000 mg / m2, BID, PO, D1-D5, QW) within the first 5 weeks. In regard to tumor immunotherapy, enrolled patients will receive tislelizumab (200 mg, iv) on the first day at week 2,5, and 8 after initiation of radiotherapy. Thereafter, patients will be treated with two 14-day cycles of the CAPOX（Q 3 w; D1 oxaliplatin, 130mg/m2,iv.gtt; D1-D14, capecitabine, 850-1000mg / m2, BID, PO）regimen. Two CAOPX regimens were treated one week apart.