BOSTON — With virtual colonoscopy expected to soon take center stage along with other colorectal screening tools, the management of colorectal polyps is poised for a major shift, according to several experts.
Virtual colonoscopy's main attraction—its minimally invasive quality—is also its main weakness. A problematic lesion that is found on virtual colonoscopy (VC) cannot be immediately removed, as it can during conventional optical colonoscopy (OC), although same-day OC with polypectomy following VC is often an option.
“The central issue is whether some of these polyps can be left,” said Dr. Joseph Ferrucci of Boston University. “Optical colonoscopy with polypectomy for all visualized polyps may be therapeutic overkill,” he said in an interview at an international symposium on virtual colonoscopy that was sponsored by the university.
Most physicians agree that small polyps (under 5 mm) can be safely left in place, and large polyps (more than 9 mm) should be removed immediately. The debate lies with medium-sized polyps measuring 6–9 mm, Dr. Ferrucci said. During OC, such polyps are normally removed because the opportunity is there, but there is no strong evidence to support this practice, and there is a growing body of evidence against it.
“The data [show] that an overaggressive approach to polypectomy has consequences. People are asking [if it's] sensible,” said Robert Smith, Ph.D., director of cancer screening for the American Cancer Society. Therapeutic colonoscopy is also much more expensive than a screening OC, he said in an interview.
Dr. Perry Pickhardt of the University of Wisconsin, Madison, said VC can act as a filter for determining the need for polypectomy. The medical school at the University of Wisconsin, one of the few to secure third-party coverage for VC, has used the tool to significantly reduce the number of polypectomies.
In a comparison of 2,202 patients receiving primary VC screening and 2,210 patients receiving primary OC screening, 7% of the VC group went on to receive an OC because of detection of a medium-sized polyp, with a resulting 325 polypectomies. The primary OC group ended up with 1,696 polypectomies. Despite that difference, the percentage of polyps identified as advanced adenomas was 3% in both groups, Dr. Pickhardt said. “VC is an effective filter for selective therapeutic OC, resulting in a more efficient use of costly and invasive resources.