There is no lymphatic metastasis in colon cancer, and the specific staging needs to depend on the extent of local tumor invasion. If the tumor only invades the submucosal layer or muscle layer of colon, clinically it belongs to stage I and does not need adjuvant chemotherapy after surgery, but if there is vascular or lymphatic vessel invasion, adjuvant chemotherapy should be administered. If the tumor penetrates into the submucosal layer and reaches the subplasma layer, invades the paracolon or pararectal tissues without peritoneal coverage, invades the dirty peritoneum, or directly invades or adheres to other organs and structures, it belongs to stage II. In stage II, if less than 12 lymph nodes are removed, if there are lymphatic vessels and vascular invasion, if the degree of pathological differentiation is low or undifferentiated, if there is perforation or intestinal obstruction before surgery, etc. Poor prognostic factors require postoperative adjuvant chemotherapy.