Flat lesions in Americans common
New research has found that not only is this type of colon lesion not as rare as once thought, it is also much more likely to turn cancerous than the polyps doctors routinely screen for.
An unusual type of colon lesion that was thought to be rare in Americans is actually relatively common and, surprisingly, is much more likely to turn cancerous than the polyps that doctors normally screen for, according to Palo Alto researchers.
Complicating the situation further is that the lesions, known as non-polypoid or flat lesions, are harder to detect during colonoscopy.
Colon cancer is the second leading cause of cancer death in the United States, with about 154,000 new cases detected each year and 52,000 deaths. But it has been believed to be almost totally preventable if doctors identify and remove polyps, which often turn into malignant tumors.
The new findings, reported Wednesday in the Journal of the American Medical Assn., indicate that gastroenterologists will have to cast a wider net during routine screening of the colon.
Polyps are distinct and obvious protuberances in the colon. The flat lesions, in contrast, are just slight bulges, even with the surface of the colon, or even depressions, and are nearly the same color as the colon walls -- making them much harder to detect. If the colon is not thoroughly cleaned with strong laxatives, they can easily be obscured.
Dr. Roy M. Soetikno and his colleagues at the Veterans Affairs Palo Alto Health Care System studied 1,819 veterans, mostly male, who underwent routine colonoscopies. The physicians were specially trained to observe flat lesions.
They found that such lesions were present in 9.35% of the veterans they studied. The flat lesions, furthermore, were associated with 15% of the potentially cancerous growths.
Removal of the lesions is also more difficult, they said, because they do not have the obvious edges of polyps. One technique to make the lesions more obvious is to spray a red dye, which stains the lesion's tissue.
thomas.maugh@latimes.com
