Many patients have rectal cancer, but they do not know the causes of this disease. The formation of rectal cancer is mainly caused by the following five reasons, which are analyzed for you one by one. Malignant transformation of benign tumor In clinical practice, we often see malignant transformation of colorectal adenoma into cancer, which indicates that the etiology of rectal cancer is extremely close to that of colorectal adenoma. 2.Polyp Most rectal cancers occur on the basis of polyps. In the normal population, the incidence of polyps is 5% to 10%, and in adults over 45 years old, the incidence of polyps is 10%, and the incidence of rectal polyps increases with age. This is also one of the causes of rectal cancer. 3.Inflammatory stimulation Due to chronic ulcerative colitis and other inflammatory diseases can cause intestinal mucosa exudation and edema, repeated destruction and repair process can lead to proliferation of fibrous tissue, thickening of intestinal wall, narrowing of intestinal lumen, interstitial changes of epithelial cells, forming multiple polyps and chronic granulomas. This is one of the more common causes of rectal cancer. 4.Dietary habits The high incidence of rectal cancer is mostly in economically more developed countries, which is not related to regional differences and racial genetic factors, but mainly to the differences in dietary habits and nutritional methods, such as the diet containing a lot of meat, fat, refined carbohydrates and the lack of refined fiber components. 5, genetic factors such as familial adenomatous polyposis, hereditary non-polyposis colorectal cancer, etc. also belong to the causes of rectal cancer. Patients with rectal cancer should pay more attention to what factors are related to the formation of rectal cancer in their life, which can not only help the treatment of rectal cancer, but also understand what causes rectal cancer, so that we can use the right method to prevent rectal cancer. Because some small details in life without attention may trigger rectal cancer.