Rectal cancer patients usually have no pain symptoms in the early stage of the disease, and when the disease progresses to the middle or late stage, lower abdominal pain symptoms may appear. If intestinal obstruction occurs, pain characteristics such as paroxysmal abdominal pain and relief of abdominal pain after evacuation may occur. Rectal cancer patients usually have no obvious symptoms in the early stage of the disease, and a small portion of patients may have symptoms such as change of bowel habit, urgency and heaviness (discomfort in the lower abdomen, wanting to defecate very much, and feeling of incomplete defecation after defecation), etc. When the disease progresses to the middle or late stage, patients may have symptoms such as pain in lower abdomen, feeling of incomplete defecation, feeling of falling down from anus, etc., and the abdominal pain symptoms usually present persistent colic pain. If the size of rectal tumor is large, the degree of abdominal pain will increase. If the tumor causes pressure on the rectum and induces intestinal obstruction, the patient may have symptoms such as intestinal flatulence and paroxysmal abdominal pain, and the pain is mainly concentrated around the navel. The abdominal pain symptoms may be relieved when the patient has bowel evacuation. If diagnosed with rectal cancer, patients are advised to go to hospital for regular treatment as early as possible to avoid delaying the condition.