Bowel cancer is a common clinical malignant tumor in the digestive tract. Compared with stomach cancer and pancreatic cancer, the symptoms of early stage of bowel cancer are relatively not obvious, so there are not only no specific 10 precursors, but also easy to be misdiagnosed or missed. Usually, if a patient shows change in bowel habit, weight loss, blood in stool, abdominal mass, gastrointestinal discomfort, etc., he/she should be alert to the possible symptoms of early bowel cancer: 1. Change in bowel habit: If a patient shows diarrhea, constipation, increased number of stools, or alternately constipation and diarrhea, he/she should pay attention to the possible early signs of bowel cancer. This is mainly due to the growth of intestinal tumor, which will directly affect the intestinal activities and cause the change of defecation habit; 2. Weight loss: In order to grow, the tumor in the early stage of intestinal cancer will absorb a large amount of nutrients in the body and affect the digestive function of gastrointestinal tract, resulting in malnutrition and then weight loss, emaciation, loss of appetite, etc.; 3. Blood in stool: If the patient intermittently has thin stool with If the patient has intermittent thin stool with purulent mucus and blood, it may be caused by malignant tumor of intestine. This is mainly because the tumor is small in the early stage and far from the anus, which may cause slight bleeding in the digestive tract, and then blood in the stool may appear intermittently. 4. abdominal mass: when touching the patient’s abdomen, it is obvious that there is a hard and movable mass, and the mass has a tendency to increase gradually, which may be caused by the combination of tumor and intestinal tissues. 5. gastrointestinal discomfort: such as abdominal distension, abdominal vague pain, indigestion and other symptoms. 5. Gastrointestinal discomfort: such as bloating, abdominal pain, dyspepsia, etc., which are not significantly different from the manifestations of gastrointestinal inflammatory diseases and are easily ignored by patients, may actually be the precursors of intestinal cancer; 6. Systemic symptoms: if patients have symptoms such as low fever, weakness, anemia, etc., they may be the systemic reaction caused by intestinal cancer.