Computed Tomographic Colonography May Be Appropriate for Surveillance of High-Risk Patients

NEW YORK, June 16, 2009 — Computed tomographic (CT) colonography may be a reasonable alternative to colonoscopy for some patients at increased risk for colorectal cancer (CRC), Italian investigators suggested.

However, results of their multicenter, cross-sectional study indicate that CT colonography is a poor first-line testing choice for patients with positive results on fecal occult blood testing (FOBT), Dr Cristiana Laudi, from the Institute for Cancer Research and Treatment in Turin, Italy, et al reported in the Journal of the American Medical Association for June 17.

The research team compared the accuracy of the 2 techniques in the detection of advanced neoplasia. The study cohort included 373 individuals with a family history of advanced neoplasia in first-degree relatives, 343 with a personal history of adenomas, and 221 with positive FOBT results. The prevalence rates of advanced neoplasia (6 mm or greater) were 7.5%, 11.1%, and 50.2%, respectively.

Overall, CT colonography had a sensitivity of 85.3%, specificity of 87.8%, positive predictive value of 61.9%, and negative predictive value of 96.3%. Sensitivity exceeded 90% for lesions measuring 10 mm or larger.

The authors proposed that, for patients at risk based on family or personal history, CT colonography may help increase the low adherence to screening guidelines and reduce the high drop-out rate during follow-up, "thus making it an effective test for increasing in absolute terms the protective effect . . . toward the development of CRC."

On the other hand, based on the high rate of neoplasia combined with the reduced negative predictive value (84.9%), Dr Laudi's team suggested, "our results do not support using CT colonography as a first-line strategy in FOBT-positive subjects."

Dr Emily Finlayson, from the University of Michigan in Ann Arbor, wrote in a related editorial that "CT colonography should be offered at centers that have the appropriate state-of-the-art equipment and are staffed by radiologists with training and experience in interpreting the images."

Still, she concluded, "With the majority of individuals in the United States who meet criteria for colorectal cancer screening and surveillance not undergoing recommended procedures, an imperfect test that has a lower-risk profile and greater acceptance among patients seems to be an appealing solution."

Source: Reuters Health Information