With the improvement of people’s living standard and change of eating habits, the incidence of colorectal cancer has been increasing, and its incidence ranks fifth in malignant tumors, after stomach cancer, esophageal cancer, liver cancer and lung cancer, especially in large and medium-sized cities. Colorectal cancer is divided into two types: colon cancer and rectal cancer. Patients with colon cancer are mostly middle-aged or above, with an average age of 45 years old, and about 5% of patients are under 30 years old. Patients with colon cancer can be asymptomatic in the early stage, but as the disease progresses, a series of cancer manifestations will appear. Clinically, the middle part of the transverse colon is used as the boundary, and the colon is divided into the left hemicolectomy and the right hemicolectomy, with different manifestations due to the different parts of the cancer. Right hemicolectomy: Because the intestinal cavity is large and the stool is liquid, most of the cancers in this section of the intestine are ulcerated or cauliflower-shaped, and there are few ring-like stenoses, so obstruction does not often occur. However, these cancers often ulcerate and bleed, with secondary infection and toxin absorption. Main clinical manifestations: 1. Abdominal pain and discomfort or abdominal pain, often located in the right lower abdomen, much like chronic appendicitis attack. If the tumor is located in the hepatic flexure and the stool is dry, colic may also occur. About 50% of the patients have loss of appetite, fullness and belching, nausea and vomiting, etc. 2, stool changes, early stool is thin, there is pus and blood, the number of bowel movements increases, related to the formation of cancer ulcers, the amount of bleeding is small, not easily visible to the naked eye, but the occult blood test is often positive. When the volume of tumor increases, it may affect the passage of stool and may alternately appear diarrhea and constipation. 3.abdominal mass, this mass may be the cancer itself, or it may be a mass formed by extra-intestinal infiltration and adhesion. 4.Anemia, emaciation or cachexia. Left hemi-colon cancer: Most of them are infiltrative type, which often causes annular stenosis, so the clinical manifestations are mainly acute and chronic intestinal obstruction. Clinical manifestations: 1. Abdominal colic is the main manifestation of cancer with acute intestinal obstruction, accompanied by abdominal distension, hyperactive bowel movement, constipation and obstructed venting, while chronic obstruction is manifested by abdominal distension, paroxysmal abdominal pain, hyperactive bowel sounds, constipation, blood and mucus in stool, and partial intestinal obstruction sometimes lasts for several months before turning into complete intestinal obstruction. 2.Difficulty in defecation, half of the patients have this symptom, and as the disease progresses, constipation becomes more and more serious. If the cancer is in a low position, there may also be poor defecation and a feeling of urgency. 3.Feces with blood and mucus. As the stool in the left hemicolectomy tends to form, blood and mucus do not mix with stool, and fresh blood and mucus can be seen in the stool of about 25% of patients with visual observation. The early symptoms of colon cancer are light or not obvious, which are often ignored by patients and therefore easily missed. Patients above middle age should be alerted to the following symptoms and consider the possibility of colon cancer: ① recent change in bowel habits (such as constipation, diarrhea or poor bowel movement), persistent abdominal discomfort, vague pain or abdominal distension; ② dilution of stool or with blood and mucus; ③ persistent positive fecal occult blood test; ④ unexplained anemia, weakness or weight loss; ⑤ lump in the abdomen. In addition to further medical history and physical examination, barium enema or fiberoptic colonoscopy should be performed immediately to exclude occupying lesions.