The geographic distribution of colorectal cancer incidence and mortality in China is characterized by a higher incidence in the eastern coastal areas than in the inland northwestern areas, with the highest incidence in the middle and lower reaches of the Yangtze River, which means that the incidence is higher in economically developed areas, higher in urban than rural areas, and higher in large cities than in small cities. However, there are also high incidence areas in rural areas. Although colorectal cancer can develop at any age, more than 90% of cases are older than 40 years old. Therefore, it is usually said that people over 40 years old should start routine medical checkups to detect possible cancer in time. 1. Dietary factors ① such as high fat and low fiber diet; ② high content of animal protein, nitrosamines and their derivatives in food; ③ intake of alcohol; ④ fried food; ⑤ vitamin A, C, E and trace element selenium deficiency, etc. Dietary factors are considered to be extremely important in the development of colorectal cancer. In the United States, since the 1950s, the advocacy of changing dietary habits led to a decline in the incidence of colorectal cancer trend also confirms this point. Certain benign lesions of the colon, such as chronic ulcerative colitis, colonic adenoma, familial colonic adenomatosis, schistosomiasis, colonic polyps, etc. The risk of colon cancer is several times higher in those who have chronic ulcerative colitis for more than 10 years than in the general population; the relative risk of colon cancer in patients with colorectal polyps is 22 times higher than in those without polyps. Genetic factors It is estimated that genetic factors may play an important role in about 20% of colorectal cancer patients, such as familial adenomatous polyposis, hereditary non-polyposis colorectal cancer is the most common hereditary colorectal cancer. Studies have found that the risk of colorectal cancer in children of colorectal cancer patients is 2-4 times higher than that of the general population, and about 10%-15% of colorectal cancer occurs in people with a history of colorectal cancer in first-degree relatives. 4.Occupational factors and health habits Lack of physical activity can increase the risk of colon cancer. However, colorectal cancer is generally not considered as an occupational disease.