Colorectal cancer is a cancer of the large intestine and rectum. It is the third most common cancer in the United States. These cancers typically form from smaller polyps which are abnormal growths on the lining of the colon. Common symptoms include a change in bowel habits, rectal bleeding, abdominal pain, or unexplained weight loss. Undergoing regular screening can reduce the risk of developing colon cancer. This is typically accomplished by testing the stool or having a colonoscopy.