This study aims to observe and evaluate the efficacy and safety of moderately hypofractionated radiotherapy combined with chemotherapy and immunotherapy, compared with conventional neoadjuvant chemoradiotherapy, in patients with high-risk locally advanced colorectal cancer.
Age ≥ 18 years and ≤ 75 years.
Histologically confirmed colorectal adenocarcinoma with the lower margin of the lesion ≤ 10 cm from the anal verge as assessed by MRI, and immunohistochemistry confirming pMMR, or genetic testing demonstrating MSI-L or MSS.
Presence of at least one of the following high-risk factors as assessed by pelvic MRI: cT4a/b; N2; extramural vascular invasion (EMVI+); mesorectal fascia involvement (MRF+); enlarged lateral lymph node (longest diameter > 7 mm).
Eastern Cooperative Oncology Group (ECOG) performance status score of 0-1
Presence of distant metastasis.
Patients with stage I or II rectal cancer who do not require preoperative neoadjuvant therapy.
Severe diseases involving the heart, lung, brain, kidney, gastrointestinal tract, or other systemic conditions.
Untreated chronic hepatitis B or HBV carriers with HBV DNA > 500 IU/mL, or patients positive for HCV RNA. Patients with inactive hepatitis B surface antigen (HBsAg) carriers, those with hepatitis B who have been treated and are stable (HBV DNA < 500 IU/mL), and those who have been cured of hepatitis C may be enrolled.