Bowel cancer is very complicated and has various symptoms, even if the stool is normal, there may be bowel cancer, which can be analyzed from the following situations: 1. When bowel cancer is relatively small, there is no clinical symptom and the stool is completely normal, so it needs colonoscopy or other examinations to be found. 2. If the tumor causes damage and bleeding of intestinal mucosa, there will also be symptoms of blood in stool, which can be fresh blood stool or may be accompanied by blood clots. 3. If the tumor grows to cause narrowing of intestinal lumen, it will make the stool thinner; if it causes change of intestinal function, it will cause constipation or diarrhea.