Colorectal cancer is a malignant lesion of the colorectal mucosa epithelium occurring under the action of various carcinogenic factors such as environment or genetics. It has poor prognosis and high mortality rate. The incidence of colorectal cancer is highest in North America, Western Europe and other places, and low in Japan, Chile and Africa. China belongs to the low incidence area. In recent years, the incidence of colorectal cancer in China has gradually increased. Especially in Shanghai and Zhejiang, which are economically developed, it is a high incidence area. The incidence ratio of colon cancer and rectal cancer is about half each. The age of incidence rate is 40~50 years old, and the high incidence age of colorectal cancer in high incidence countries is 60~70 years old. The age of colorectal cancer in China is 10-15 years earlier than that in foreign countries, which is one of the main characteristics of colorectal cancer in China. The incidence rate of colorectal cancer in men is significantly higher than that in women, which is about 1.6:1. The 5-year survival rate after surgical resection can reach 40% to 60% on average. Early detection, early diagnosis, early treatment and standardized surgical treatment are still the keys to improve the efficacy of colorectal cancer. The causes of colorectal cancer are not yet clear, but may be related to the following factors. 1. Environmental factors: dietary factors are the most important, and the incidence of colorectal cancer is positively related to the high fat consumption in food. In addition, it may also be related to the lack of trace elements and change of living habits. 2, genetic factors: There are reports of “colorectal cancer familial” at home and abroad, and the number of people who died from this disease among blood relatives of colorectal cancer patients is significantly higher than the general population. Some colorectal adenoma, such as multiple familial adenomatosis, is an autosomal dominant disease with a prevalence of up to 50% in the family. 3, colorectal adenoma: According to the autopsy materials around the study, the incidence of colorectal adenoma is quite consistent with colorectal cancer. According to statistics, the incidence of colorectal cancer in patients with one adenoma is five times higher than those without adenoma, and the incidence of multiple adenomas is one time higher than that of single adenoma patients. 4. Chronic inflammation of the colon: Inflammatory changes in the intestine due to schistosomes, some of which will become cancerous. Other chronic inflammatory diseases of the intestine also have the possibility of cancer, such as ulcerative colitis, about 3% to 5% of which are cancerous. 5.Parasitic diseases: Our information shows that some advanced schistosomiasis is also complicated by colorectal cancer. 6.Age: The average age of colon cancer patients is between 60-65 years old. The older the patient is, the greater the danger of colon cancer. Common symptoms of colorectal cancer: Rectal cancer is firstly manifested by rectal irritation symptoms, increased number of stools, unshaped stools, thin stool shape and effortful defecation. At the later stage, blood in stool may appear, with more volume and dark red color, accompanied by mucus, and some of them are even mucus and blood stool. If there is obstruction of the intestinal cavity, then there will be symptoms of intestinal obstruction, abdominal pain, abdominal distension, stopping bowel movement and exhaustion. Be careful not to confuse rectal cancer blood in stool with hemorrhoids. Hemorrhoid bleeding is mostly fresh blood, usually in small amounts, usually dripping after stool, and does not mix with stool. Colon cancer is mainly manifested by consumption, for example, anemia, emaciation, weakness, low fever and other manifestations, and masses can be palpated in the abdomen. In early stage, colon cancer is mostly manifested by change of stool habit, alternating dry stool and diarrhea, dark red blood in stool, mixed with stool, and symptoms of intestinal obstruction in late stage: abdominal pain, abdominal distension, stopping defecation and exhaustion. Which people need to be alert to colorectal cancer? 1.People aged 30 to 40 years old or above, more common above 60 years old, with gastrointestinal symptoms. 2.People who have a history of colorectal cancer. 3.People with precancerous colorectal lesions such as adenoma, ulcerative colitis, schistosomiasis; people with family history of cancer, family history of polyps, hereditary colon disease. 4.Patients with history of pelvic radiotherapy. 5.People with history of gallbladder or appendix removal. Tips: People with the above factors should have regular medical checkups, stool occult blood examination and anal finger examination once a year, and colonoscopy is feasible when necessary. Prevention of colorectal cancer: An important way to prevent colorectal cancer is to maintain a healthy diet and eat more yams, sweet potatoes, corn, fruits, fresh vegetables and other foods rich in carbohydrates and coarse fibers, which have a short residence time in the intestine and facilitate the elimination of intestinal toxins. Try to eat less fried, smoked, high-fat and high-protein foods, and do not eat fruits, vegetables and foods that are likely to spoil. Maintain a healthy lifestyle: increase exercise appropriately, maintain a regular rhythm of life, quit smoking and drinking, and control weight. Active treatment of colorectal diseases such as ulcerative colitis and intestinal adenoma is also very crucial. Treatment of colorectal cancer: The treatment effect of early colorectal cancer is very ideal, with a 5-year survival rate of over 90% after surgery, while the 5-year survival rate of advanced colorectal cancer is less than 50%. Therefore, early detection and timely treatment is an effective way to improve the cure rate of colorectal cancer. Once colorectal cancer is diagnosed, the only effective treatment method is surgery to remove the tumor, and for patients with progressive cancer, adjuvant treatment such as chemotherapy is also needed. Different surgical methods are used according to different parts of the tumor, such as right hemicolectomy, left hemicolectomy, sigmoid colectomy, and radical rectal cancer surgery (including anal preservation and non-anal preservation). The surgical methods can be divided into traditional open surgery and laparoscopic surgery. Laparoscopic surgery has the advantages of less trauma, less bleeding, faster recovery of intestinal function and shorter hospital stay, and the curative effect and long-term survival rate are similar to those of traditional surgery. Postoperative precautions: Colorectal cancer patients should choose the quality and quantity of diet reasonably after the surgery. The postoperative recovery diet generally starts from drinking water, gradually over to liquid diet and semi-liquid diet. After recovery, it is appropriate to use high-protein, high-calorie, low-fat and easily digestible food, and add or subtract additions according to stool properties, frequency and volume, etc. Spicy and stimulating food is prohibited, and it is better to have a light diet and not to eat greasy food. Early after rectal surgery patients will experience disorders of intestinal function, most commonly diarrhea, followed by constipation, which generally relieves significantly after 3 to 6 months after surgery and requires no special treatment. For those who have a lot of diarrhea, consider antidiarrheal medication for symptomatic treatment.