Polyps are benign growths (noncancerous tumors or neoplasms) involving the lining of the bowel. They can occur in several locations in the gastrointestinal tract but are most common in the colon. They vary in size from less than a quarter of an inch to several inches in diameter. They look like small bumps growing from the lining of the bowel and protruding into the lumen (bowel cavity). They sometimes grow on a “stalk” and look like mushrooms. Some polyps can also be flat. Many patients have several polyps scattered in different parts of the colon. Some polyps can contain small areas of cancer, although the vast majority of polyps do not.