The option of a virtual colonoscopy encourages substantially more people to undergo screening than when conventional colonoscopy was the only option, according to a new study.

Researchers at the Academic Medical Center (AMC; Amsterdam, The Netherlands) and Erasmus University Medical Center (Rotterdam, The Netherlands) conducted a randomized, population-based trial involving 5,924 people, ages 50 to 75, who were invited for primary screening for colorectal cancer. A further 2,920 were offered the option of a computerized tomography (CT) colonography without cathartic bowel preparation. Invitations were sent between June 8, 2009, and Aug 16, 2010. Those assigned to CT colonography who were found to have one or more large lesions (over 10 mm) were offered colonoscopy; those with 6-9 mm lesions were offered surveillance CT colonography. The primary outcome was the participation rate, defined as number of invitees undergoing the examination relative to the total number of invitees.

The results demonstrated different response rates among procedures; 34% of people offered CT colonography were screened, compared with only 22% of those offered standard colonoscopy; this worked out to a relative risk for screening of 1.56 favoring the CT-based procedure. Of the participants in the colonoscopy group, 9% had advanced neoplasia, of whom seven (<1%) had a carcinoma. Of CT colonography participants, 9% were offered colonoscopy, of whom 6% had advanced neoplasia; five of them (<1%) had a carcinoma; 8% were offered surveillance. Serious adverse events related to the screening procedure were postpolypectomy bleedings: two in the colonoscopy group and three in the CT colonography group. The study was published early online on November 15, 2011, in the Lancet Oncology.

“Participation in colorectal cancer screening with CT colonography was significantly better than with colonoscopy, but colonoscopy identified significantly more advanced neoplasia per 100 participants than did CT colonography,” concluded lead author Evelien Dekker, MD, and colleague of the department of gastroenterology and hepatology. “The diagnostic yield for advanced neoplasia per 100 invitees was similar for both strategies, indicating that both techniques can be used for population-based screening for colorectal cancer.”

Virtual colonoscopy is a procedure used to look for signs of precancerous growths, cancer, and other diseases of the large intestine. Images are taken using CT or, less often, magnetic resonance imaging (MRI). A computer puts the images together to create an animated, three-dimensional (3D) view of the inside of the large intestine.

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