Will Colonoscopy Soon Be Out of Date?

The need for colonoscopy, rather than sigmoidoscopy (just the lowest part of the large intestine) and stool blood tests, has been emphasized as the best way to screen for colo-rectal cancer. There’s no doubt, however, that colonoscopy is a not-very-pleasant procedure – especially the bowel cleanout beforehand. “Virtual colonoscopy” – an animated, 3-D view of the large intestine built by computer from CT scans – is touted as a substitute for a real colonoscopy, but it’s generally agreed that it’s not quite as effective in picking up lesions, and it doesn’t include the possibility of a biopsy.

Now Mayo Clinic researchers have studied a new stool test that tests for specific DNA from the common tumors throughout the gastro-intestinal (g.i.) tract. They presented the results at the Digestive Disease Week 2009 meeting. A total of 138 patients (69 cases with g-i cancers, and 69 age/sex-matched controls with a normal colonoscopy) provided stool samples. The cancers included colon, esophagus, stomach, pancreas, bile duct, gall bladder and small bowel. The DNA stool test was positive in 68% of the patients with cancer and negative in all the control patients. Among the positive test subjects, those with stomach and colo-rectal cancer were 100% positive, with the other cancers recording 62% to 75% positive test results.

This study was the first look at this approach for detecting more than one g-i cancer. It’s highly encouraging, and, if replicated in further studies, will shift the strategy of cancer screening to become a multi-organ procedure. Indeed, it’s a major step forward.