New DNA Stool Testing Spots More Colon Cancers

Oct. 9 -- WEDNESDAY, Oct. 8 (HealthDay News) -- A new and improved DNA stool sample test to screen for colon cancer is twice as effective at catching cancer and serious precancerous polyps than either current blood stool sample tests or an older version of DNA testing, new research reveals.

"This is a very important finding in that if you don't detect the precancerous lesions, you don't actually prevent cancer," said Dr. David A. Ahlquist, a professor of medicine, and a gastroenterology consultant at the Mayo Clinic in Rochester, Minn.

"The problem increasingly sensitive DNA testing addresses is that blood as a marker for colon cancer has limitations," he explained. "Because most polyps basically don't bleed. In contrast, all precancerous polyps shed cells that contain abnormal DNA. So, a stool-based DNA test is a strategically more rational approach."

The finding was reported in the Oct. 7 issue of the Annals of Internal Medicine.

Ahlquist stressed that he and his team have "no commercial attachments whatsoever" to the new DNA stool test method, while noting that the study was supported by grants from the National Institutes of Health.

Though considered curable if detected early and before spreading, the authors point out that colorectal cancer ranks as the second most common cause of death among cancers in the United States, following lung cancer.

At the moment, several screening options exist, including radiographic imaging; invasive colonoscopy (involving insertion of a flexible tube into the colon); and the testing of stool samples for signs of blood and/or abnormal DNA shed by the colon. All these methods seek to uncover evidence of the precancerous growth of polyps on the lining of the colon, which develop anywhere from five to 10 years before cancer itself.

Yet despite the availability of such screening tools, the research team observed that more than half of American adults have never undergone colorectal cancer screening. This fact, they suggest, highlights the need for more user-friendly testing methods.