Virtual colonoscopy (also known as CT colonography or CTC) is an effective and less invasive alternative to conventional colonoscopy for individuals at elevated risk of colorectal cancer, according to the published results of a multicenter study in Italy that was first reported on AuntMinnie.com in 2007.
The authors of the study in the June 17 Journal of the American Medical Association said that because VC is easier tolerated than conventional colonoscopy, it could help improve screening compliance in this population (JAMA, June 17, 2009, Vol. 301:23, pp. 2453-2461).
Dr. Daniele Regge from the Institute for Cancer Research and Treatment in Turin, Italy, and colleagues evaluated CT colonography for detecting advanced colorectal neoplasia in asymptomatic individuals at increased risk of colorectal cancer, compared with conventional colonoscopy as a reference standard. Elevated risk was defined as individuals with a higher risk of colorectal cancer due to a family history of advanced neoplasia (n = 373) in first-degree relatives, personal history of colorectal adenomas (n = 343), or positive results at fecal occult blood testing (FOBT) (n = 221).
Of 1,103 participants, 937 were included in the final analysis: 373 cases in the family-history group, 343 in the group with personal history of adenomas, and 221 in the FOBT-positive group. The prevalence of advanced neoplasia was 7.5% in the family-history group, 11.1% in the postpolypectomy group, and 50.2% in the FOBT-positive group.
CT colonography identified 151 of 177 participants with advanced neoplasia 6 mm or larger (sensitivity, 85.3%), and correctly classified true-negative results in 667 of 760 participants (specificity, 87.8%). The positive and negative predictive values were 61.9% and 96.3%, respectively. The negative predictive values ranged from 84.9% in the FOBT-positive group to 98.5% in the family-history group.
The results "suggest a potentially effective use of CT colonography as an alternative to colonoscopy for screening individuals with family history of advanced colorectal neoplasia," Regge and colleagues wrote. "Computed tomographic colonography has been shown to be better accepted than colonoscopy and has a negligible risk of serious adverse events; thus, it may help increase the low adherence reported for individuals who are candidates for screening, which is the main negative factor affecting its efficacy in reducing mortality from [colorectal cancer]."
Related Reading
CMS rejects Medicare coverage for virtual colonoscopy, May 12, 2009
Need for VC colon screening trumps physician turf battles, January 20, 2009
American Cancer Society recognizes virtual colonoscopy screening benefit, March 5, 2008
ACR teams with iCAD on CAD CT colonography, January 22, 2008
Italian multicenter VC trial screens higher-risk cohort, November 17, 2007
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