Certain types of polyps may warrant keeping closer tabs on the colon

Starting at age 50, or earlier with certain risk factors, patients are advised to be screened for colon cancer at regular intervals. Colonoscopy is an effective screening test because it allows doctors to find and view individual polyps (growths), and to remove them before they become cancerous.

Adenomas are polyps (small growths in the lining of the colon) that can vary in their size and shape, but are potentially precursors to colon cancer. Removal of these polyps reduces the risk of colon cancer. Flat adenomas are precancerous polyps that do not have a typical polyp- like appearance during endoscopy.

A new study in GIE: Gastrointestinal Endoscopy, the journal of the American Society for Gastrointestinal Endoscopy (ASGE), "Prevalence of advanced histological features and synchronous neoplasia in patients with flat adenomas," indicates that a patient who had at least one flat adenoma had a higher chance of having multiple lesions with more advanced changes.

The researchers looked at data from three clinical trials conducted at two medical centers that included patients undergoing screening or surveillance colonoscopy. The location, size, form and structure of each removed polyp was documented and sent for microscopic examination.

A total of 2931 polyps were removed in 1340 patients. Of the 1911 adenomas (65.2%), 293 (15.3%) were flat. The analysis showed that the presence of at least one flat adenoma was a predictor of the presence of a large adenoma, adenomas with advanced microscopic features, and three or more adenomas.

The authors concluded that flat adenomas are associated with more frequent occurrence of large and advanced adenomas as well as multiple adenomas appearing at the same time. This could mean that patients with these results should be examined more often and more closely than patients with other types of polyps.