The main symptoms of rectal cancer include blood in stool, abdominal pain, abnormal bowel movement and weight loss. The color of blood in stool is mostly bright red or dark red, and the blood is mostly attached to the surface of stool, sometimes the blood in stool cannot be distinguished by naked eyes alone, and can only be detected by stool occult blood. The abdominal pain is usually vague or swelling pain, which is not obvious in the early stage but more obvious in the later stage. Abnormal bowel movements mainly include anal swelling, feeling of incomplete defecation, increased frequency of defecation, and thinning of stool with mucus or blood. When the rectal cancer tumor is larger, it can narrow the intestinal cavity, resulting in thin stool and difficult defecation, and in serious cases, it will block the intestinal cavity and prevent defecation and exhaustion. Patients with mid- to late-stage rectal cancer may also have symptoms such as weight loss, general weakness and even fever. The early symptoms of rectal cancer are not obvious, and the initial symptoms are mostly painless blood in stool or mucus and blood in stool, and the number of stools increases, which is less painful to patients and therefore often neglected.