Neoadjuvant CAPOX Plus Tislelizumab vs CAPOX in MSS High-Risk Locally Advanced Colon Cancer

Inclusion Criteria:

* Age ≥18 years old and ≤75 years old.
* Pathologically diagnosed MSS ((confirmed by microsatellite stable detection or next-generation target sequencing) or (confirmed by immunohistochemistry)) colon adenocarcinoma.
* The lower edge of the tumor is more than 12cm from the anus as measured by colonoscopy and the lower edge of the tumor cannot be directly palpated during rectal examination.
* Enhanced CT stage T4 or T1-4 N+ without multiple primary tumors or distant metastasis.
* The Eastern Cooperative Oncology Group physical status score is 0-1.
* Life expectancy is expected to be more than 1 year.
* First diagnosis, no previous anti-tumor treatment received, and no chemotherapy contraindications.
* Appropriate organ function is defined as follows: Hemoglobin level ≥ 60g/L, Neutrophil count ≥ 1.5×10\^9/L, Platelet count ≥ 75×10\^9/L, Serum total bilirubin ≤ 1.5× the upper limit of normal (UNL), Aspartate aminotransferase (AST) ≤ 2× UNL, Alanine aminotransferase (ALT) ≤ 3× UNL, Serum creatinine ≤ 1.5× UNL.
* Informed consent, able to understand the study protocol and willing to participate in the study, and will provide written informed consent.

Exclusion Criteria:

* Enhanced CT stage (T1-3N0M0)
* Multifocal colorectal cancer.
* CT or MRI in the mid-sagittal plane shows that the lower border of the tumor is below the line connecting the sacrococcygeal promontory and the upper border of the pubic symphysis.
* Tumor obstruction or high risk of obstruction, bleeding, and/or perforation requiring emergency surgery or stent placement.
* Cannot tolerate chemotherapy or immunotherapy, such as but not limited to bone marrow suppression.
* History of malignant tumors, except for basal cell carcinoma, papillary thyroid carcinoma, and various in situ cancers.
* Acute exacerbation of important organ diseases (such as but not limited to chronic obstructive pulmonary disease, coronary heart disease, and renal insufficiency) and/or severe acute infectious diseases (such as but not limited to hepatitis, pneumonia, and myocarditis), American Society of Anesthesiologists score \> 3 points.
* Mental disorders, illiteracy, or language communication barriers that prevent the understanding of the study protocol.
* Peripheral sensory neuropathy, unable to receive oxaliplatin-based chemotherapy.
* Continuous use of glucocorticoids for more than 3 days within 1 month prior to signing the informed consent form, or having comorbidities requiring the use of glucocorticoid therapy.
* Unable to undergo enhanced CT examination
* Pregnancy or lactation.
* Refused to participate in this study.
* Other situations in which the researcher deems unsuitable for this study.