CAPOX and PD-1 Antibody Combined With or Without Radiotherapy for MSS Locally Advanced Rectal Cancer

Inclusion Criteria 1. Age 18-70 years old, female and male; 2. Pathological confirmed adenocarcinoma; 3. The distance from anal verge ≤ 10 cm; 4. MSI/MMR status: MSS/pMMR; 5. Clinical stage T3-4 and/or N+, without distance metastases; 6. At least one of the following factors is present: distance from the anus ≤5 cm, cT4, cN2, positive cMRF, positive cEMVI, or positive lateral lymph nodes; 7. KPS ≥ 70; 8. No radiotherapy, chemotherapy, immunotherapy, or any other anti-tumor therapy had been administered prior to enrollment; 9. Baseline blood and biochemical indicators meet the following criteria: neutrophils ≥ 1.5 × 10\^9/L, Hb ≥ 90 g/L, PLT ≥ 100 × 10\^9/L, ALT/ AST ≤ 2.5 ULN, Cr ≤ 1 ULN; 10. With good compliance and signed the consent form. Exclusion Criteria 1. Pregnancy or breast-feeding women; 2. Known history of other malignancies within 5 years; 3. Known history of severe neurological or mental illness (such as schizophrenia, dementia or epilepsy); 4. Current severe cardiac disease (cardiac dysfunction and arrhythmia), renal dysfunction and liver dysfunction; 5. Acute cardiac infarction or cerebral ischemic stroke occurred within 6 months before recruitment; 6. Uncontrolled infection which needs systemic therapy; 7. Active autoimmune disease or immunodeficiencies, known history of organ transplantation or systematic use of immunosuppressive agents; 8. Known history of human immunodeficiency virus (HIV) infection (i.e., HIV 1 to 2 antibody positive), active syphilis infection, active pulmonary tuberculosis infection; 9. Allergic to any component of the therapy.