Before the surgery of intestinal cancer, it is usually necessary to do systemic examination, including heart function, lung function, coagulation function and blood clotting function, which is called comprehensive examination, to judge the early and late stage of tumor, including CT examination of lung and liver before the surgery, and CT examination of tumor site to see whether there is liver metastasis, whether there is lung metastasis, and whether the local tumor invasion is outside. In addition, it is very important to do colonoscopy before surgery, preferably colonoscopy of the whole colon, to see where the tumor is located. If only the distal colon cancer is removed and the proximal colon cancer is not treated, it will definitely recur in the future, and the early cancer may become advanced.