1. Dietary factors: such as high fat and low fiber diet; high content of animal protein, nitrosamines and their derivatives in food; alcohol intake; fried food; vitamin A, C, E and selenium deficiency of trace elements, etc. Dietary factors are considered to be extremely important in the development of colorectal cancer. In the United States, this is also confirmed by the declining trend of colorectal cancer incidence due to the advocacy of dietary changes since the 1950s. In contrast, in China, with the increasing improvement of people’s living standards, the national diet has also undergone great changes, with high-fat, high-protein and high-calorie foods increasing in the menu. This is also the reason for the increasing incidence of colorectal cancer in China. 2.Some benign lesions of the colon: such as chronic ulcerative colitis, colonic adenoma, familial colonic adenomatosis, schistosomiasis, colonic polyps, etc. The risk of colon cancer in people with chronic ulcerative colitis for more than 10 years is several times higher than in the general population, because the repeated inflammation in the intestine is a chronic stimulation of the intestinal mucosal cells, and this stimulation over time can lead to uncontrolled growth of mucosal cells and malignant changes. The relative risk of colorectal cancer is 22 times higher than that of those without polyps, because although polyps themselves are benign, they may become malignant. 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 is 2-4 times higher for children of colorectal cancer patients than for 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, it is generally not considered that colorectal cancer is an occupational disease. Colorectal cancer prevention Among the many causative factors of colorectal cancer, what we can change is the dietary habits, the high incidence of colorectal cancer in economically developed areas, which is mainly related to their dietary structure, that is, the so-called “Western cultural diet”, which is high in animal protein, high fat diet, too fine diet, such as beef, less Fiber and refined rice and flour. This is mainly because the fat and its breakdown products in food may have carcinogenic or synergistic carcinogenic effects. A diet with too little fiber can reduce the amount of stool and make the stool pass through the intestine for a significantly longer period of time, so as to increase the concentration of synergistic carcinogens in the stool and prolong the contact time with the colonic mucosa significantly, and the long-term contact between carcinogens and the colonic mucosa may lead to carcinogenesis.