The main objective of this study was to evaluate the effect of surgical margin width on the prognosis of patients with hepatic oligometastasis of colorectal cancer by statistical 1-year intrahepatic recurrence-free survival rate (ihRFSrate). The secondary objective of the study was to evaluate the effect of surgical margin width on long-term survival and total recurrence of colorectal cancer in patients with hepatohepatic metastasis by statistical overall survival time (OS) and relapse-free survival time (RFS), and to evaluate the safety of wide margin surgery compared with narrow margin surgery in patients with Cromitis during perioperative period.

This was a single-center, prospective, randomized controlled clinical study to evaluate the effects of surgical margin width on 1-year intrahepatic relapse-free survival, relapse-free survival time, overall survival time, and perioperative safety in patients with hepatic oligometastasis of colorectal cancer. Subjects will undergo radical resection of liver tumors and will be randomly assigned to a wide margin group (≥7mm) or narrow margin group (<7mm) using stratified randomization, stratified by primary lesion site (right colon vs left colon/rectum). The margin width was the narrowest margin distance measured in fresh specimens. After radical liver tumor resection, subjects were pretreated regularly Follow-up evaluation.

Inclusion Criteria:

• Male or female patients, age ≥18 years;
• ECOG Physical condition score :0-1 score;
• Liver biopsy pathologic diagnosis or clinical history combined with laboratory examination and imaging findings can be used to diagnose colorectal cancer in liver;
• The primary lesion of colorectal cancer has been resected or can be resected 4-6 weeks after hepatectomy;
• The number of liver metastases was less than or equal to 5；
• There was no extrahepatic metastases or the metastases were radically resected；
• Preoperative assessment (based on enhanced CT or MRI image AI segmentation combined with three-dimensional reconstruction of hepatic parenchymal blood vessels) enables radical (R0) resection of hepatic oligometastases, and wide surgical margin (the narrowest incisal margin of fresh specimens surgically removed is greater than or equal to 7mm) can be achieved technically, and the incisal margin width is not affected by the intrahepatic vasculature；
• Good liver reserve function (preoperative Child-Pugh grade A liver function, estimated remaining liver volume ≥30%)；
• Preoperative examinations do not show clear surgical contraindications；
• Volunteer to participate in this study and sign the informed consent；
• The compliance was good, and the family members were willing to cooperate with the follow-up；

Exclusion Criteria:

• There are still untreated extra-hepatic metastases；
• Staging hepatectomy is planned, such as PVE combined with hepatectomy, ALPPS, etc；
• The number of liver metastases before chemotherapy was more than 5；
• Complicated with portal vein tumor thrombus or hepatic vein invasion；
• Concurrent with other uncured malignancies or with other primary malignancies for less than 5 years；
• Expected survival time ≤6 months；
• Those who have a history of psychotropic substance abuse and are unable to abstain or have mental disorders；
• Have a history of immunodeficiency or other acquired or congenital immunodeficiency diseases; Or have an autoimmune disease；
• According to the study, there are serious concomitant diseases that endanger the patient's safety or interfere with the patient's completion of the study；
• Patients or family members could not understand the conditions and goals of the study；