Colon Polyp Size and Cancer Risk

Colon Polyps & Cancer Risk

A colon polyp is an irregularity of the internal lining of the colon. It most commonly results in a raised surface or bump on the inner surface of the colon. Polyps are common in American adults, and while many colon polyps are harmless, over time, some polyps could develop into colon cancer.

While the majority of colon cancers start as polyps, only 5-10% of all polyps will become cancerous. The size of a polyp typically does make a difference. The larger the polyp becomes, the bigger the risk of it developing into colon cancer. That risk increases significantly if the polyp is greater than 10 mm (1 cm); research has shown the larger a colon polyp becomes, the more rapidly it grows.

"Most polyps do not typically cause symptoms, and they don't go away on their own. Therefore, the only way to know if they are there is to test for them. This is why colonoscopy exams are essential for preventing cancer," says Kevin Robillard, MD, Associate Professor of Oncology in the Department of Gastroenterology at Roswell Park Comprehensive Cancer Center.

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"Most polyps will be removed during the colonoscopy. Once removed, how a polyp looks under the microscope (during the pathology exam) determines the appropriate follow up.  The larger the polyp is, the harder it is to remove it. There are special techniques to remove larger polyps and sometimes a person will be referred here for removal either with endoscopy or sometimes with surgery."

Because colon polyps can be removed before they become cancerous, it makes colonoscopies one of the only tests available that can actually prevent cancer. However, this happens only by properly following the colorectal cancer screening guidelines. Roswell Park follows the American Cancer Society recommendations that both men and women begin receiving a routine colonoscopies starting at age 45. There are some patients that have higher risk and need to start earlier. Also, there are other tests besides colonoscopy that can be considered. Colonoscopy is the most accurate test and the only one that removes polyps, so this is often the test chosen. Talk to your primary care physician about colon cancer screening. 

"What is found during colonoscopy, family history and a patient's medical history influences decisions on follow up testing in the future," says Dr. Robillard. "By following colorectal cancer screening guidelines, we can discover colorectal cancer at an earlier stage or even better, prevent cancer from ever developing in the first place!"