Bowel cancer, which includes colon and rectal cancer, often causes changes in the character of the stool. According to different locations of tumors, the performance is also different. 1. Colon cancer: change of bowel habit and fecal character can be seen in early stage, which is common in left half colon cancer, and can be manifested as increased frequency of bowel movement, diarrhea, constipation, feces with blood, pus or mucus. 2. Rectal cancer: no obvious symptoms in early stage. In the late stage, the tumor may obstruct the intestinal lumen or rupture and bleed, resulting in frequent bowel movement, incomplete bowel movement, blood in stool, thinning of feces, mucus stool, pus and blood in stool. If there is a sudden change of bowel habit or the nature of feces, or diarrhea and constipation alternately, one should consult a doctor as soon as possible to improve the colonoscopy and other related examinations, so as to make a clear diagnosis of the disease, and treat the disease as soon as possible in order to gain a better prognosis.