Catching the Cancers Colonoscopies Miss

March 5, 2008— -- Doctors today were taking a hard look at how colonoscopy may change in light of new data which suggests many potential cancers are being missed -- and the research may even impact how colonoscopy is done and how patients perform the distasteful preparation for the procedure.

Coincidentally, the findings came on the same day a group of medical organizations recommended two tests -- virtual colonoscopy and a stool DNA test -- to supplement traditional colonoscopy screening tests for colon cancer.

But ironically, neither of these new additions are adequate for detecting the flat, non-polyp lesions that the new research, published Wednesday in the Journal of the American Medical Association, suggests could pose a huge a risk for colon cancer.

Researchers at the Veterans Affairs Palo Alto Health Care System studied 1,819 patients who underwent a colonoscopy. The study found nearly one in 10 of the patients had nonpolyp lesions, and that these lesions were 10 times as likely to contain cancerous cells as the traditional polyps.

Moreover, these nonpolyp lesions are much harder to find and to remove than regular polyps because they are flat and are often the same color as the healthy tissue surrounding them.

Japanese researchers published studies about these flat lesions in the 1980s and 1990s, but until now, American doctors tended to think that the flat, nonpolyp lesions were signals of a type of colon cancer that is less common in the United States. However, these new findings provide evidence that this type of colon cancer is also prevalent here.

Dr. Douglas Rex, medical director of endoscopy at the Indiana University Hospital, said the findings suggest doctors must become more aware of this type of lesion and be on the lookout for its telltale signs.

"In this study, these lesions were seen using widely available colonoscopes and careful examination," said Rex. "These tools are available to everyone doing colonoscopy — they just need to be used."

In addition to better using the equipment available for traditional colonoscopies, Dr. Len Lichtenfeld, deputy chief medical officer for the American Cancer Society, said the new findings should convince many endoscopists to take a longer time to perform the procedure with utmost attention to detail.