Rectal cancer is cancer between the dentate line and the junction of the rectosigmoid colon, and is one of the most common malignant tumors of the gastrointestinal tract. The location of rectal cancer is low, so it can be easily diagnosed by rectal finger diagnosis and sigmoidoscopy. However, because of its location deep into the pelvic cavity and complex anatomical relationship, surgery is not easy to be complete and the recurrence rate after surgery is high. The proximity of lower and middle rectal cancer to the anal sphincter makes it difficult to preserve the anus and its function during surgery, which is a difficult problem in surgery and is also the most debated disease in terms of surgical methods. The median age of rectal cancer incidence in China is around 45 years old. There is a trend of increasing incidence among young people. Who are vulnerable to rectal cancer? People living in areas with high incidence of colorectal cancer: the incidence of colorectal cancer has obvious geographical characteristics, with low incidence in some areas and high incidence in others. 2.Patients with rectal adenoma: Although rectal adenoma is a benign tumor, it can malign into colorectal cancer, and its cancer rate is related to various factors such as tumor size and pathological typing, etc. Multiple adenomas have more chances of cancer than single adenoma. 3.Schistosomiasis patients: patients with schistosomiasis proctitis are prone to rectal cancer. 4.Patients who have received radiation treatment in pelvis: their rectum is more prone to cancer than normal people. 5.Family members of rectal cancer patients: the genetic tendency of rectal cancer is more obvious than other GI cancers, and the prevalence of the disease among blood relatives of rectal cancer patients is higher than that of the general population. 6.Patients with inflammatory proctology: Patients with ulcerative proctitis or clonorchiasis that do not heal for a long time (generally more than 10 years) may have rectal cancer. In addition, people who have suffered from rectal cancer may have rectal cancer again despite surgical removal of the lesion or anti-cancer treatment by internal medicine, and there are more men than women with rectal cancer, and the incidence of rectal cancer increases significantly around the age of 40.