The early symptoms of colon cancer mainly include discomfort and pain in the lower abdomen, which does not necessarily become more pronounced after eating and generally occurs intermittently. Some patients may also experience changes in stool shape, primarily manifested as narrower stools, or an increased frequency of bowel movements per day, leading to diarrhea. Some patients in the early stages may experience worsening of pre-existing constipation, or alternating symptoms of diarrhea and constipation. Some colon cancer patients in the early stages may experience bloody stools, or the presence of mucus, pus, and blood in the stool, which are some atypical gastrointestinal symptoms of colitis. Some patients may also experience nausea.