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Updated: September 7, 2006

This villous adenoma picture was derived from the Gastrointestinal Atlas (www.gastrointestinalatlas.com)

Picture of a Villous Adenoma

Donna Myers 2006

An adenoma is a benign tumor that develops from epithelial tissue. Adenomas in the colon are often referred to as adenomatous polyps. Although adenomas aren't cancerous, they have the potential to become cancerous.

Adenomas and Colon Cancer

Most colorectal cancer develops from adenomatous polyps. Adenomas that turn into cancer are referred to as adenocarcinomas.

Colon cancer screening helps identify and remove adenomas before they become a problem.

Size of Adenomas

The bigger the adenoma, the greater its chances of being cancerous. For example, if a colonoscopy were to find an adenoma in your colon the size of a nickel, there'd be a 30-50% chance that it would be cancerous. You can learn more about polyp size and colon cancer risk by viewing the Polyp Size Gallery.

Types of Adenomas

There are three types of adenomas: tubular, tubulovillous, and villous. Tubular adenomas are the most common and, as you might guess, have a tube-like structure. Villous adenomas are the least common and have sort of a ruffled, frilly structure. Tubulovillous adenomas are a mix between the two and occur less frequently than tubular adenomas but more frequently than villous adenomas.

Related Articles: Sources:
  1. Adenoma. Biology Online. 7 Sep. 2006 [http://www.biology-online.org/dictionary/Adenoma].
  2. Adenoma. Merriam-Webster Online. [http://m-w.com/dictionary/adenoma].
  3. Colonic Polyps. El Salvador Atlas of Gastrointestinal Video Endoscopy. 7 Sep. 2006 [http://www.gastrointestinalatlas.com/English/Colon_and_Rectum/Polyps/polyps.html].
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