Rectal cancer can be clinically divided into early stage and middle and late stage. Most early stage patients will not show special symptoms, and most early stage rectal cancer is found during routine physical examination. In contrast, patients in the middle and late stages will show obvious symptoms, as follows: 1. rectal irritation symptoms: such as frequent bowel movements or anal cramping; 2. intestinal stricture symptoms: such as thinning of stool, grooves or intestinal obstruction symptoms in serious cases; 3. other symptoms: such as blood in stool or perforation due to tumor rupture, peritonitis symptoms will appear accordingly. In more advanced rectal cancer, if the tumor invades the bladder or prostate, symptoms of urinary frequency, urinary urgency and hematuria will appear. If it is accompanied by bone metastasis, the symptoms of sacrococcygeal pain will appear.