If the index of carcinoembryonic antigen increases during the five tumor tests, it may indicate that the patient has intestinal cancer, which usually requires colonoscopy or CT examination of the abdomen and pelvis. Carcinoembryonic antigen is one of the more sensitive tumor indicators in gastrointestinal tract, usually high carcinoembryonic antigen may suggest that patients have bowel cancer, but normal carcinoembryonic antigen does not completely exclude that patients do not have bowel cancer, so when patients have five tumor tests, if there is any abnormality, colonoscopy is recommended, generally colonoscopy can detect lesions inside the intestinal tract, and pathological examination can be taken to confirm the diagnosis of patients with bowel cancer. If polyp or adenoma is found inside the intestine during the colonoscopy, it is recommended to remove it as much as possible because polyp and adenoma may become malignant after a long time.