| Similar adenoma detection rates with CT colonography and optical colonoscopy By Reuters Health September 22, 2008 NEW YORK (Reuters Health), Sep 22 – Colorectal adenoma miss rates are comparable for CT colonography (CTC) and optical colonoscopy (OC), according to a report in the August American Journal of Gastroenterology. “No screening test is perfect,” Dr. Patrick Pfau from University of Wisconsin-Madison School of Medicine and Public Health told Reuters Health. “CTC will miss polyps, particularly sessile polyps, but the miss rate of polyps on CTC is not different than the miss rate of polyps on colonoscopy.” Pfau and colleagues performed optical colonoscopy on 159 patients who had positive screening CTC examinations (one or more polyps greater than 5 mm). These 159 patients had 230 polyps seen on CTC and 359 seen on colonoscopy. The 137 additional polyps not seen or not reported (because of size below 5 mm) on CTC accounted for 38.2% of all polyps found by colonoscopy. Twenty-five of the additional lesions (found in 21 patients) were adenomas; the remainder were hyperplastic polyps. These findings correspond to a per-patient missed adenoma rate of 13.2% and a missed per adenoma rate of 18.9%, the researchers said. Four missed polyps (in four patients) were advanced adenomas (based upon a size of 10 mm or more). No cancerous lesions were missed by CTC. These miss rates, the investigators say, are “comparable to the 13% (5-10 mm) and 2.1% (>10 mm) adenoma miss rate reported in a recent review of studies examining miss rates in tandem colonoscopy studies. Our findings are also similar to the 14% and 10% miss rates of adenomas 6 mm or greater missed by CTC and optical colonoscopy, respectively, when CTC followed an optical colonoscopy exam.” “CTC gives patients another test option (a test option that doesn’t require sedation) that can detect polyps at similar accuracy to colonoscopy,” Pfau said. “However, the weakness of CTC is that it is solely a diagnostic test and not a therapeutic test. If polyps are seen on CTC, the patient still needs a colonoscopy for polyp removal.” Further studies, Pfau said, will assess the accuracy of CTC in size of polyps, compare CTC screening and colonoscopy screening for total adenoma detection rate, examine the natural history of polyps not resected and followed by CTC, and investigate the pathology of medium-sized polyps (6-9 mm) found on CTC. By Will Boggs, MD Am J Gastroenterol 2008;103:2068-2074. |