Neoadjuvant Immunotherapy for T4 dMMR Colon Cancer

Inclusion Criteria:

1. Aged 18-75 years;

2. ECOG score 0-2;

3. Adenocarcinoma confirmed by pathology and dMMR confirmed by IHC or PCR;

4. Tumor located in cecum, ascending colon, transverse colon and sigmoid colon;

5. Patients with clinical stage cT4: (1) Loss of space between tumor and adjacentorgans or invasion of adjacent organs as assessed by enhanced CT; (2) R0 resectioncannot achieve according to intraoperative exploration;

6. No evidence of distant metastasis;

7. Newly treated patients who have not received treatment including chemotherapy andsurgery;

8. Liver, kidney and other organs have good function and can tolerate chemotherapy andsurgery;

9. Patients and family members can understand the study protocol, voluntarilyparticipate in the study and sign informed consent.

Exclusion Criteria:

1. A history of other malignant tumors (other than cured basal cell carcinoma, cervicalcarcinoma in situ, surgically treated localized prostate cancer, or surgicallyresected breast ductal carcinoma in situ) within the past 5 years;

2. Complicated with intestinal obstruction, intestinal perforation, gastrointestinalbleeding and other patients requiring emergency surgery; pregnant or lactatingwomen;

3. Patients with a history of severe mental illness, immune disease, hormonemedication;

4. Patients contraindicated by immunotherapy or surgery;

5. Participated in other clinical researchers in the past 3 months;

6. Any other circumstances that the investigator considers inappropriate for inclusion.