Rectal cancer is a common malignant tumor of the digestive system. The causes of rectal cancer in clinical practice include the following: First, some benign diseases of the rectum, such as adenomatous polyps, are precancerous lesions of rectal cancer. Second, genetic factors also play an important role in the incidence of rectal cancer. Epidemiological surveys show that the incidence of rectal cancer is significantly higher in populations with a family history of rectal cancer. Third, chronic inflammatory diseases of the rectum, such as ulcerative rectitis and Crohn's disease, can also lead to a significantly higher incidence of rectal cancer compared to the general population. Fourth, the incidence of rectal cancer is also somewhat related to viral infections of the rectum or radioactive damage.