Rectal cancer lacks symptoms in the early stage, and patients have no obvious abnormal changes. When the mass reaches 1-2cm, due to the erosion of the tumor, the intestinal mucosa suffers from foreign body stimulation of the mass and the secretion increases, so a small amount of mucus is discharged during defecation, mostly at the front of the stool or attached outside the stool. As the tumor increases, the mucus secretion also increases. Sometimes, with the increase of intra-abdominal pressure by exhaustion or sudden coughing, mucus may flow out from the anus. When the tumor increases and forms ulcers or necrosis combined with infection, there will be obvious symptoms of rectal irritation and changes in the number of bowel movements and nature of stools. The number of bowel movements increases to 2-3 times a day, with mucus stools, thin stools or mucus and blood stools. It is often misdiagnosed as “enteritis”, “dysentery”, “ulcerative colitis” and so on. However, the diarrhea symptoms of rectal cancer are not like colitis, which has a rapid onset and quick improvement; nor is it like dysentery, which has typical symptoms of urgency. The rectal irritation symptoms of rectal cancer are both slow and progressive, and the irritation symptoms are obvious when combined with infection, which can be temporarily improved after symptomatic treatment, but those who still have mucus and blood stools after longer treatment should be given sufficient attention. Patients should go to the hospital for detailed examination when the following conditions occur: 1, abnormal stool habits: the number of bowel movements increases, along with a small amount of mucus stool, mucus blood stool, after treatment does not improve, or after treatment improves but relapses, should be promptly diagnosed and treated. 2, previous history of mucus stool, diarrhea: but the symptoms are mild suddenly increased, with the original number of bowel movements, the nature of the bowel movement has changed, should also be re-examined to confirm the diagnosis. 3, no obvious reason for constipation and diarrhea alternately: after short-term treatment without improvement, in the stomach after barium fluoroscopy did not find abnormalities, should go to the hospital to do rectal site examination. 4, straining to defecate: the expelled stool has pressure marks, grooved flat strips, thin strips, etc. must be done rectal finger diagnosis. Any of the above four conditions should be promptly checked in the hospital. Where available, it is best to ask a surgeon or anorectologist to check.