Dr. Cristiana Laudi, from the Institute for Cancer Research and Treatment in Turin, and her associates conducted a multicenter, cross-sectional study that used CT colonography for patients with positive results on fecal occult blood testing (FOBT). The results showed that CT colonography was poor first-line testing choice.
The study cohort compared the the accuracy of the two techniques in the detection of advanced neoplasia in 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 rates of prevalence 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 suggested that CT colonography for patients at risk based on family or personal history 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 suggests, 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, Ann Arbor, writes 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 concludes, 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.
