Rectal cancer is more insidious in its onset, and in the early stage, it usually has no obvious symptoms, does not have stomach pain, and the first changes in defecation habit and fecal character appear, after which abdominal pain symptoms may appear due to the lesions. 1. Change of bowel habit and fecal character. Generally, it is the earliest symptom of rectal cancer, which may include bloody stool, constipation, thinning of stool, diarrhea and other symptoms. 2. Abdominal pain. It may cause dull pain in the right abdomen, and the lesion may cause gastro-colonic reflex to be strengthened, leading to postprandial abdominal pain, which may be aggravated after the occurrence of intestinal obstruction. In addition, when rectal cancer is in middle or late stage, symptoms of abdominal mass may appear, accompanied by anemia, low fever, emaciation and other symptoms. When suffering from rectal cancer, it should be actively treated under the guidance of professional doctors to improve the quality of survival and prolong the survival period.