Colon Polyps

Colorectal (Colon) Cancer Slideshow Digestive Disease Myths Slideshow

Medical Author: Michael Santoro, M.D.
Medical Reviewing Author/Editor: Dennis Lee, M.D.

• What is a colon polyp?
• What types of polyps become cancerous?
• Are there other factors that determine a polyp's chance of becoming cancerous?
• What other types of polyps are there in addition to adenomas?
• What are the guidelines for screening individuals for polyps in order to prevent colon cancer?
• What kind of additional surveillance should be done once a polyp has been found?
• What happens if a polyp that is removed contains cancer?
• Is one's risk of having colon cancer increased by having had an adenoma?
• What is one's risk of having a polyp or cancer if a first-degree relative (parent, sibling, or child) has had an adenomatous polyp?
• Are there ways to prevent colon polyps from developing?
• What does the future hold for screening and surveillance of colon polyps?
• Are there situations in which polyps carry a very high risk of becoming cancerous?
• What about genetic counseling and testing?
• Colon Polyps At A Glance
• Pictures of Colorectal (Colon) Cancer - Slideshow
• Pictures of Digestive Disease Myths - Slideshow
• Patient Discussions: Colon Polyps - Describe Your Experience

What is a colon polyp?

Colon polyps are fleshy growths that occur on the inside (the lining) of the large intestine, also known as the colon. Polyps in the colon are extremely common, and their incidence increases as individuals get older. It is estimated that 50% of the people over the age of 60 will harbor at least one polyp. The significance of polyps is that we know that when certain types of polyps grow large enough, they can become cancerous, and, moreover, colon cancer is the second leading cause of death from cancer in the United Sates. Therefore, screening for colon polyps and removing them before they become cancerous should markedly reduce the incidence of colon cancer.

What types of polyps become cancerous?

The polyps that become cancerous are called adenomatous polyps or adenomas. Adenomas account for approximately 75% of all colon polyps. There are several subtypes of adenoma that differ primarily in the way the cells of the polyp are assembled when they are examined under the microscope. Thus, there are tubular, villous, or tubulo-villous adenomas. Villous adenomas are the most likely to become cancerous, and tubular adenomas are the least likely.

Are there other factors that determine a polyp's chance of becoming cancerous?

Another factor that contributes to a polyp's likelihood of becoming cancerous is its size. The larger a polyp grows, the more likely it is to become cancerous. Once a polyp reaches two centimeters or approximately one inch in size, the risk of cancer is in excess of 20 percent. Therefore, it is advisable to remove polyps of any size, preferably when they are of a small size, to prevent their growth and progression to cancer.

Next: What other types of polyps are there in addition to adenomas? »

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