Guidelines may misclassify high-risk findings.
The study included 10,034 colonoscopies performed over a 5-year period at Indiana University. Dr. Rex and his colleagues applied the 2005 ACR guidelines to the colonoscopy results, which included 10,780 polyps that were removed. The researchers had access to the size and histology of each polyp that was removed, Dr. Rex said at Digestive Disease Week.
According to the ACR guidelines, polyps 5 mm or smaller in size should not be reported on CT colonography (CTC), resulting in a normal finding if no larger polyps are seen. Patients with one or two polyps that are 6-9 mm in size can be offered CTC surveillance in 3 years, instead of a colonoscopy with polypectomy.
High-risk findings include three or more adenomas of any size, adenomas with villous or tubulovillous histology, those with high-grade dysplasia, and adenomas greater than or equal to 1 cm in size, according to surveillance recommendations from the U.S. Multisociety Task Force and the American Cancer Society. Patients with high-risk findings should have a repeat colonoscopy with polypectomy 3 years after the initial exam, according to the guidelines.
Among all the patients in the database, 51% (5,079) had at least one polyp, and 29% (2,907) had at least one adenoma. Ten percent (1,001) had high-risk findings.
Overall, out of those with high-risk findings, there were 293 patients (29%) with either three adenomas less than 5 mm, or an advanced adenoma less than 5 mm and no larger polyp of any histology in the colon. These 293 patients would have been regarded as normal on CTC, said Dr. Rex, who is Chancellor's Professor and professor of medicine at Indiana University, Indianapolis, and director of endoscopy at Indiana University Hospital.
There were 2,174 patients over age 50 years; 326 (15%) had high-risk adenoma findings. Of that high-risk group, 33% (108) had either three or more adenomas less than 5 mm in size, or an advanced adenoma less than 5 mm in size and no polyps greater than 6 mm in size. Again, those 108 patients would have been told that they had normal findings.
The Indiana researchers also found that 18% of all patients with high-risk findings, and a similar number of patients over age 50 with high-risk findings, could have been inappropriately told to delay a colonoscopy for at least 3 years. These patients had either three adenomas less than or equal to 9 mm, or an advanced adenoma less than or equal to 9 mm in size, or both and no polyp of any histology that was 10 mm or larger.
Following the ACR guidelines, "the bottom line is about 33% of everyone with high-risk adenoma findings would be told they were normal and another 20% would be told they could wait at least 3 years" before another CTC, Dr. Rex said.
Dr. Rex disclosed that he is a speaker for Olympus America Inc. and that he receives grant support from Given Imaging Ltd.
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|Publication:||Internal Medicine News|
|Article Type:||Clinical report|
|Date:||Aug 1, 2008|
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