A polyp is a projecting mass of overgrown tissue. It looks a lot like an inflated balloon, with the part you tie off attached to wherever it's growing from.
Virtually all colorectal cancer develops from adenomatous polyps, generally referred to simply as polyps. Colon Polyps and Cancer Risk provides more information about why colorectal polyps increase the risk of developing cancer.
The Polyp Size Index lets you see what polyps look like and how big they are in real life. The gallery helps illustrate why you can't count on noticing that polyps is present.
- Buetow, P. and Buck, J. "Colorectal Adenocarcinoma." RadioGraphics 15.1 (Jan. 1995). 28 Aug. 2006 [http://www.rsna.org/REG/publications/rg/afip/privateM/1995/0015/0001/0127/1.htm#topAnchor].
- Detailed Guide: Colon and Rectum Cancer: What Are the Risk Factors for Colorectal Cancer? American Cancer Society. 7 Mar. 2006. 28 Aug. 2006 [http://www.cancer.org/docroot/CRI/content/CRI_2_4_2X_What_are_the_risk_factors_for_colon_and_rectum_cancer.asp].