MRD-Guided Surveillance in Resectable Stage IV Metastatic Colorectal Cancer (SURVEILLANCE-II)

Inclusion Criteria:

1. Age 18-80 years old, male or female;
2. histologically confirmed primary foci of colorectal adenocarcinoma (i.e., adenoepithelial carcinoma, including adenocarcinoma, mucinous adenocarcinoma, imprinted cell carcinoma, and undifferentiated carcinoma; excluding adenosquamous carcinoma); (3) Preoperative stage IV and no surgical resection; (4) Not receiving chemotherapy, radiotherapy, targeted therapy or other anti-tumor therapy;

5\) Surgical resection of primary/metastatic foci is possible; 6) ECOG score 0-1; 7) Subjects voluntarily enrolled in the study and signed the informed consent, good compliance, and actively cooperate with the regular clinical follow-up clinic back in the hospital.

Exclusion Criteria:

1. Previous other malignant tumors (including non-adenocarcinoma colorectal cancer);
2. Pregnant and lactating women;
3. Patients with other concurrent illnesses that, in the judgment of the investigator, may interfere with follow-up and short-term survival;
4. The subject has other factors that may cause this study to be forced to be terminated halfway, such as other serious illnesses (including psychiatric illnesses) that require comorbid treatment, serious laboratory test abnormalities, accompanied by family or social factors that would affect the safety of the subject, or the collection of data and samples.