1.Blood in stool: Intestinal tumor will rupture and bleed when the tumor in the intestinal cavity is stimulated by stool, so blood in stool or positive fecal occult blood is often an early signal of colorectal cancer. During the physical examination, the stool test indicates “OB positive”, after excluding hemorrhoids, we should attach great importance to the possibility of intestinal tumor. Reminder: Many rectal cancer patients are mistakenly treated as hemorrhoids in the early stage! 2. Change in bowel habits: diarrhea, constipation without any regularity, sudden appearance and change in bowel habits excluding gastroenteritis should be considered for colonoscopy. Reminder: Early colorectal cancer can be cured! 3. Abdominal pain: Abdominal pain caused by colorectal tumor is mostly in the middle and late stage, and the abdominal pain of colorectal cancer is mostly found in the right side of abdomen, when the unexplainable right side persistent abdominal pain, the possibility of colorectal cancer should be highly suspected! 4.Abdominal mass: If you feel an abdominal mass, especially the right side of the abdomen, under normal stool condition, you should have ultrasound first screening and further colonoscopy if necessary. CEA (carcinoembryonic antigen) is a test item generally required in health checkups, and most of the normal reference values are from 0 to 5. If CEA is higher than the normal value, you should find an oncologist for related consultation!