Adenomatous polyps are a type of abnormal growth in the colon. While most colon polyps do not cause any problems, adenomatous polyps are thought to be the source of most colorectal cancer.

Adenomatous polyps usually grow very slowly. It may be years before they turn into cancer, if they ever do. They usually are discovered during a routine sigmoidoscopy or colonoscopy and are removed. Having adenomatous polyps in the colon means that the person will need to be screened for colorectal cancer more often than a person who has no polyps.