Colon cancer and rectal cancer combined are known as colorectal cancer. Most colorectal cancers develop from colon polyps in the intestinal lining. If detected early, colorectal cancer can be cured. Colon cancer symptoms include blood in the stool and changes in bowel habits, but early disease may not have symptoms. Screening tests, such as colonoscopy, may result in early detection before symptoms develop. Other gastrointestinal (GI) system cancers include pancreatic cancer, liver cancer, stomach cancer and esophageal cancer. Diet, smoking , chronic acid reflux and family history may increase cancer risk.