Colon cancer is a malignant tumor occurring in the colon, with a high incidence at the age of 41-51. More than half of colon cancer is caused by adenoma, and morphological changes of proliferation, adenoma and cancer stages and corresponding chromosomal changes can be seen. With the development of molecular biotechnology, it is clear that the development of cancer is a multi-step, multi-stage and multi-gene genetic disease. Colorectal cancer evolves from cells to carcinoma, from adenoma – cancer sequence through about 10-15 years. Causes of colon cancer: The causes of colon cancer are not yet clear, but high fat, high protein, low dietary fiber diet; lack of moderate physical activity are high risk factors for colon cancer. Meanwhile, genetic susceptibility also has an important position in the development of colon cancer, for example, family members carrying mismatch repair gene mutation in hereditary non-polyposis colon cancer are regarded as the high-risk group for colon cancer development; some diseases such as familial intestinal polyposis are recognized as precancerous lesions; and colonic adenoma, ulcerative colitis and colonic schistosomiasis granuloma are more closely related to the occurrence of colon cancer. Treatment of colon cancer: the principle is a comprehensive treatment mainly based on surgical resection. 1.Radical surgery for colon cancer: For resectable colon cancer, this operation is the preferred surgical method, and the resection scope includes intestinal collaterals where the cancer is located, its lining and regional lymph nodes. The scope of colon resection depends on the tumor site, the intestinal segment to be resected and its arterial feeding area and lymphatic drainage area. Complete resection can be considered curative only. 2.Surgery of colon cancer with acute intestinal obstruction: Colon cancer with acute intestinal obstruction should be treated by surgery at an early stage after proper preparation such as gastrointestinal decompression, correction of water-electrolyte disorder and acid-base balance. Right hemicolectomy and ileocolic anastomosis should be performed for right hemicolectomy. If the patient’s condition does not allow, cecum fistula can be done first to contact the obstruction, and radical surgery can be performed in the second stage. If the cancer cannot be resected, the terminal ileum can be cut off, and a proximal ileo-transverse colonic anastomosis and distal ileostomy can be performed. In case of acute intestinal obstruction complicated by left-sided colon cancer, transverse colostomy is generally performed at the proximal end of the obstruction, and radical resection is performed under the condition that the intestine is fully prepared. If the tumor cannot be removed, palliative colostomy will be performed. 3.Treatment of colon cancer with metastasis to liver, lung and other surrounding organs: about 50-60% of colon cancer patients will have metastasis, and about 15-25% of patients will have simultaneous liver metastasis. Studies have shown that selective surgical resection of liver metastases in patients with liver metastases from colon cancer still has the possibility of obtaining a cure; therefore, for most patients with liver metastases from colorectal cancer, the goal of treatment should be radical cure. A 5-year survival rate of more than 50% after resection of liver metastases from colon cancer has been recently reported. For potentially resectable liver and lung metastases that are initially resectable or can be transformed by chemotherapy, surgical resection is the standard of local treatment. Therefore, in the management of liver metastases from colorectal cancer, it is particularly important to determine whether patients with metastases are suitable for surgical resection or potentially suitable for surgical resection and the subsequent selection of surgical cases. The current criterion for determining whether a patient with liver metastases is suitable for surgical resection is whether negative surgical margins can be obtained based on preservation of adequate normal liver reserve function. Surgery should be considered only if it allows complete resection of all known lesions, as partial resection or reduction of liver metastases has been shown to have no survival benefit. If the patient is amenable to surgery and feels that the liver or lung metastases are resectable, the recommended management is: colectomy with concurrent or staged liver (lung) resection; 2-3 months of neoadjuvant chemotherapy followed by colectomy and concurrent or staged liver/lung resection; or colectomy followed by neoadjuvant chemotherapy (as above) followed by staged resection of the metastases. Patients with single metastasis in the lung that can be surgically resected should be considered for colon resection first, followed by staged open-heart surgery to remove the lung nodes. 4. Treatment of recurrent colon cancer: the first choice of treatment for recurrence of colon cancer after surgery is surgical resection. For recurrent cases of colon cancer, those who can tolerate surgery, even those who have recurred for many times after surgery, should actively perform surgery and strive for radical resection, which is an important means to improve the cure rate and prolong the survival. For those who have recurrence of extensive implantation metastasis in abdominal cavity or pelvis and cannot be resected radically, the main implantation metastasis can be removed to reduce the tumor load, so as to improve the general condition and facilitate the comprehensive treatment such as intraperitoneal or intravenous chemotherapy. 5.Minimally invasive surgery for colon cancer: it refers to laparoscopic assisted radical surgery for colon cancer. Current domestic and foreign literature reports show that its treatment effect is similar to that of traditional open surgery. It has gradually become a method of colon cancer surgery due to the advantages of less trauma, less bleeding and faster postoperative recovery. Since this technique requires the operator to have good lumpectomy skills, the expert group recommends that laparoscopic-assisted colectomy should be performed by a surgeon with extensive experience; it must be able to perform a full abdominal exploration. Laparoscopic surgery should not be used in patients with acute intestinal obstruction or perforation, significant localized peripheral tissue-organ infiltration, or risk of severe abdominal adhesions. If severe abdominal adhesions are found during laparoscopic exploration, they should be referred to open surgery. 6. Diet and nutrition after partial colectomy: The main function of the colon is to absorb water, store and transfer stool, and also absorb glucose, electrolytes and some bile. The absorption function mainly occurs in the right colon. The surgical site of colon cancer patients is in the colon, which has little impact on the absorption function. In the early postoperative period, as the intestinal peristalsis has not yet recovered, intravenous infusion should be used to replenish nutrition. Once intestinal peristalsis is restored, enteral nutrition should be restored as soon as possible to maintain intestinal barrier and improve immune function, so as to reduce complications. 7. Care of fistula after colon cancer resection: the main purpose of gastrointestinal fistula is to relieve obstructive symptoms and prepare for later surgical resection. Ensure good blood circulation in the fistula and no bleeding and necrosis. The intestinal canal is protected with Vaseline – iodoform gauze around it until the wound is completely healed. Use a false anal pouch and pay attention to the color, nature and amount of drainage fluid in the pouch, and to the smoothness of exhaustion and defecation. Perform anal dilation once a day to prevent stricture. Pay attention to the protection of the skin around the drainage opening, reduce the irritation of intestinal fluid and the occurrence of eczema. For skin ulceration around the fistula, intestinal mucosa edema, ischemic necrosis, ectopic prolapse or invagination, which are related to the stimulation of fecal pollution and poor blood supply to the intestinal tube of the fistula, attention should be paid to observation and timely treatment. 8.Survival rate of colon cancer after surgery: the prognosis of colon cancer is good, and the 5-year survival rate of Dukes A, B and C stage is about 80%, 65% and 30% respectively after treatment by radical surgery. The earlier the tumor stage is, the better its healing.