Colon cancer is a type of cancer that grows in the colon, or large intestine.
In most cases, colon cancer begins as a polyp and grows into a tumor if left untreated. Colon cancer strikes both men and women. Although it is more common after age 50, it can develop in younger people as well. People with colon cancer often report a change in their bowel habits. This is more than a change that occurs over a day or two.