Not all colorectal cancer patients have elevated carcinoembryonic antigen, but some of them are within the normal range. Bowel cancer may have many symptoms, such as deformation or thinning of stool, blood in stool, abdominal pain, abdominal discomfort or change in stool habit, such as diarrhea, constipation or alternating diarrhea and constipation. When one or more of the above symptoms appear, you need to go to the hospital for colonoscopy as soon as possible, and if a mass is found under the colonoscopy, a biopsy should be taken for pathological examination. If the pathology confirms that it is bowel cancer, a reasonable treatment plan should be formulated according to the specific clinical stage.