I. Right hemicolectomy 1. Indications: Progressive cecum cancer Ascending colon cancer Cancer of the hepatic flexure of the colon. 2. Scope of resection: resection of the cecum, ascending colon and right one-half of the transverse colon as well as the ileum 15 cm long from the ileocecal part. The ileocolic vessels and right colonic vessels should be cut at the root, and the root of the right branch of the middle colonic artery and the root of the colonic branch of the common stem of the stomach and colon should be cut. The corresponding large omentum connected with the transverse colon should be excised. 2.Radical surgery for transverse colon cancer 1.Indication: progressive transverse colon cancer. 2. Scope of resection: all transverse colon including hepatic flexure and splenic flexure of the colon, extending to the upper part of ascending colon and descending colon if necessary. The blood vessels in the colon and the ascending lymph nodes of the right colon and left colon are cut from the root. Remove all large omentum on the gastric side and remove subpyloric lymph nodes if necessary. Left hemicolectomy 1.Indications: progressive descending colon cancer, cancer at the junction of descending colon and sigmoid colon. The scope of resection: left 1/3 of transverse colon, upper 2/3 of descending colon and sigmoid colon; the left branch of middle colonic artery, left colonic artery and sigmoid artery should be cut at the root, and the lymph nodes around the submesenteric vessels should be removed. The upper 2/3 of the sigmoid mesentery and the left 1/3 of the transverse colonic mesentery as well as the greater omentum are excised. Sigmoid colon cancer radical surgery 1.Indications: progressive sigmoid colon cancer. 2. Scope of resection: resection of intestinal canal more than 10 cm from each side of tumor edge. Cut off the inferior mesenteric vessels at the root, and remove the sigmoid lymph nodes, superior rectal lymph nodes and descending lymph nodes of the left colon. Complete resection of the mesentery of the sigmoid colon. V. Radical rectal cancer resection A (transabdominal perineal rectal cancer resection Miles operation) 1. Indications: Progressive rectal cancer and/or rectoanal cancer with the lower edge of the tumor within 5-6 cm from the anal edge. 2. Scope of resection: resection of the entire rectum, anal canal and 15 cm long intestinal canal at the upper edge of the tumor for artificial anus. Cut off the inferior mesenteric vessels at the root, remove all the sigmoid mesentery below the two upper sigmoid vessels, and remove most of the posterior pelvic wall peritoneum including all the rectal mesentery. The anus and a certain range of perianal skin were excised, the superior rectal artery was cut at the root, and the lymphatic fatty tissue in the sciatic rectal fossa was removed. If necessary, lateral lymphatic dissection is performed. Radical rectal cancer resection B (transabdominal rectal cancer resection anterior rectal resection Dixon operation) 1.Indications: Progressive rectal cancer with the lower edge of the tumor more than 7 cm from the anus. 2. Scope of resection; resection of tumor and 15 cm of rectum and sigmoid colon proximal to the tumor and 2-3 cm of rectum distal to the tumor. Remove the entire rectal mesentery, or at least the rectal mesentery within 5 cm from the distal side of the tumor. Dissect the submesenteric vessels from the root and remove all sigmoid lymph nodes and pararectal and superior rectal lymph nodes. The large part of the sigmoid mesentery and the pelvic peritoneum more than 3 cm on either side of the rectum are removed. Lateral lymphatic dissection may be required for ultra-low anterior resection.