Pathology is not a passive observer in the debates about the effectiveness of virtual colonoscopy versus standard colonoscopy. After all, at some point, tissue collected by gastroenterologists as a result of either procedure must be examined by pathologists to confirm the presence of colon cancer and other diseases.
It has been argued that virtual colonoscopy, because it is a non-invasive procedure, would encourage more adults to undergo the test. That would increase screening rates for colon cancer. Proponents of virtual colonoscopy got a boost with new research published in the September 18, 2008 issue of New England Journal of Medicine [Vol 359:1207-1217], moving this test a step closer to acceptance by the medical community, as well as insurers.
In the largest study yet of this controversial test for colorectal cancer, lead researcher C. Daniel Johnson, M.D., of the Mayo Clinic in Scottsdale, Arizona, reported that virtual colonoscopy, which involves a CT scan of the lower body, proved effective in detecting both large and medium-size polyps, which can lead to colon cancer.
The study involved 2,600 men and women at 15 medical sites, including academic centers and community medical centers. All participants received both virtual and standard colonoscopy, 99% of which received both tests on the same day. Virtual colonoscopy successfully identified 90% of polyps or cancers 10 mm (one centimeter) or larger detected with traditional colonoscopy. “These findings augment published data on the role of CT colonography in screening patients with an average risk of colorectal cancer,” concluded Dr. Johnson.
Virtual colonoscopy eliminates the discomfort associated with standard colonoscopy, as well as the need for anesthesia and risk for bowel perforations, which occur in 1 of 1,000 patients. This new research may cause insurers to get onboard, as CT colonography: 1) costs about half as much as standard colonoscopy; 2) because it is performed on an outpatient basis; and, 3) does not require the services of an anesthesiologist.
Researchers believe a simple, non-invasive test like this would overcome barriers to screening people for colon cancer and save many lives. This noninvasive test still requires patients to prepare by taking a bowel cleanser, but does not involve the discomfort or embarrassment associated with the invasive procedure, which involves inserting a camera mounted on a flexible tube into the lower intestine.
Approximately 4% of patents screened will have polyps one centimeter (10 millimeters) or larger, which must be removed to prevent cancer, and 12% of patients have polyps six millimeters or larger. Virtual colonoscopy has a 14% false positive rate and proponents note that this is comparable to other accepted screening tests.
It is estimated that only about half of the 70 million people at risk for colon cancer have been screened. This huge market for colon cancer screening is recognized by the nation’s two largest laboratory companies. Each has introduced proprietary tests for colorectal cancer screening into the market. Anatomic pathologists would benefit from an increased number of case referrals should a growing number of consumers decided to take advantage of virtual colonoscopies as a colon cancer screening tool.