At the early stage of bowel cancer, blood is the main symptom, followed by change in stool habit, incomplete bowel movement, urgency and heaviness, etc. In addition, it is very likely to cause obstruction and irritation of intestinal tract. There are many prominent clinical manifestations of bowel cancer, so patients need to be more careful. In the early stage of bowel cancer, blood in stool is mainly painless, and the blood is red or bright red, which is very similar to the symptoms of early internal hemorrhoids; in the later stage, blood in stool is mostly dark red, mixed with mucus and blood of stool or pus and blood. Secondly, change of stool habit is a typical manifestation of middle and late stage of intestinal cancer. Due to rectal mass and its secretion, it can produce symptoms of intestinal irritation, resulting in frequent bowel movement, incomplete bowel movement, urgency and heaviness, but the discharge is mostly mucus-pus-blood, and the shape of stool has changed at this time, and the stool is getting thinner and thinner. 3. As the cancer infiltrates around the circumference of the intestinal wall, the intestinal cavity is narrowed, especially at the junction of rectosigmoid colon, which is mostly a narrow type of hard cancer, and it is very easy to cause obstruction. Patients with advanced rectal cancer, due to long-term chronic consumption of the disease, will appear some systemic cachexia. In addition, unexplained anemia may appear. Patients must pay attention to timely examination and treatment in professional hospitals for unexplained wasting, weakness and loss of appetite. 4.Intestinal cancer often invades the surrounding tissues and organs, such as bladder and prostate gland and other adjacent tissues, causing urinary frequency, urinary urgency and difficulty in urination. Invasion to the presacral plexus causes pain in the sacrococcygeal and lumbar areas. Rectal cancer can also metastasize to the liver, causing hepatomegaly, ascites, jaundice, and even malignant fluid.