CT colonography (CTC), or virtual colonoscopy, is more effective than the traditional X-ray test with a barium enema, and should be considered along with colonoscopy as an alternative to investigate possible colon cancer, according to a study published Feb. 14 in The Lancet.
A second study published on the same day also suggests that for most patients, CTC provides a similarly sensitive, less invasive alternative to colonoscopy, but that guidelines are needed to reduce the referral rate after CTC.
In the first trial, more than 3,800 patients were randomly assigned to receive either a barium enema test or a CTC. The researchers found that CTC missed just three of 45 colorectal cancers, while the barium enema missed 12 of 85.
"Our trial shows that CTC is more accurate than barium enema," joint-lead researcher Steve Halligan, M.D., of the University College London, said in an announcement. "We hope that barium enema will now be phased out in favor of CTC and that NICE will update its guidelines. Although CTC can be performed on standard CT scanners available in practically all NHS hospitals, many do not have radiologists experienced with looking at CTC scans. These radiologists will need training in order to deliver the results we observed in our trials."
In the second trial, 1,580 patients were assigned to receive either a CTC or a colonoscopy. The detection rates of colorectal cancer or large polyps were the same for both procedures, but in the patients who had CTC, 30 percent had follow up tests. While some of these follow-up tests were ordered to investigate large polyps or possible cancers that were seen during the CTC, other follow-up tests were ordered to investigate small polyps that may not develop into cancers.
"Understandably hospital doctors are cautious in requesting more tests after CTC," lead author Wendy Atkin, Ph.D., said. "However, CTC detects unimportant findings, so guidelines are needed to help doctors decide who should have a further test. With these in place, we have shown that CTC offers a viable option for people who are not able to or do not wish to undergo a colonoscopy for whatever reason."