CHICAGO (AP) - Flat growths on the colon wall are more common in Americans than previously thought and more likely to be cancerous than the more familiar knobby masses known as polyps, a new study finds.
New techniques can locate and remove the flat growths, but many doctors aren't aware of their cancer risk and may not know how to look for them. The findings are likely to change the practice of colonoscopy, experts said, and may explain some colon cancers that arise between colonoscopies.
"I think it is very important. It's going to intensify the need for quality screening," said Dr. Stephen Hanauer, gastroenterology chief at the University of Chicago, who was not involved in the study. "You're not going to be able to do seven-minute colonoscopies."
The growths tend to be smaller when they are cancerous - the size of a nickel instead of a quarter - and are level with the colon wall or depressed like a pothole. They blend in with the surrounding tissue and are difficult to spot.
Doctors have known about flat growths but haven't recognized their danger, experts said.
While knobby polyps were found in four times as many participants, more than half the colon cancers found - 15 of 28 - were in flat and depressed growths. Thirteen were in polyps.
Researchers found the flat growths were nearly 10 times more likely to be cancerous than the polyps. They believe the growths represent a separate colon cancer pathway, rather than being precursors to knobby polyps, Soetikno said. The study appears in Wednesday's Journal of the American Medical Association
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