Reduced Dissemination of Tumor Cells With Primary Ligation of the Inferior Mesenteric Vein in Rectal Cancer Patients.

Inclusion Criteria: Age: 18-75 years; Histopathologically confirmed as rectal adenocarcinoma(tumor located within 15 cm from the anal verge at colonoscopy); Patients with a stage I-III rectal cancer eligible for surgery and R0 resection is expected, patients with pelvic lateral lymph nodes metastasis are ineligible; ECOG score: 0-1; ASA score: I/II/III; Laparoscopic surgery; Informed consent. Exclusion Criteria: Patients who have received preoperative treatment (such as preoperative radiotherapy and chemotherapy); Receiving transanal total mesorectal excision (taTME), specimen extraction through natural lumen (NOSES) ; Recurrent rectal cancer; Simultaneous or metachronous colorectal cancer; Malignant tumors of other organs in the past 5 years or at the same time; The results of preoperative physical examination and imaging examination showed that: (1) the tumor involved the surrounding organs and required combined organ resection; (2) distant metastasis; (3) could not be resected at R0; Pregnant or lactating women; Patients with severe mental disorder; It is not suitable for patients undergoing laparoscopic surgery (such as extensive adhesion caused by previous abdominal surgery or inability to tolerate artificial pneumoperitoneum); History of unstable angina pectoris or myocardial infarction in the past 6 months; Have a history of cerebrovascular accident in the past 6 months; Systemic administration of corticosteroids within 1 month before enrollment; Taking folic acid related drugs within half a year before operation. Severe cardiac insufficiency (FEV1<50% of predicted values); Emergency surgery.