Objective: We assessed the utility of computed tomography colonography (CTC) in primary screening for colorectal cancer in comparison with that of total colonoscopy (TCS).
Methods: A total of 5,341 subjects (3,242 males and 2,099 females, mean age 55.8 ± 10.8 [range 18 – 89]) who underwent primary screening for colorectal cancer using CTC from April 2010 to March 2017 were included in our study. We calculated the recall rate, consultation rate, tumor detection rate, positive predictive value, and cancer detection rate for CTC and compared them with those for TCS in primary colorectal cancer screening during the period 2003–2016. We also evaluated the screening for extracolonic diseases by CTC.
Results: With CTC, the recall rate, consultation rate, tumor detection rate, positive predictive value, cancer detection rate, and detection rate for first examination for colorectal cancer were 9.4% (500/5,341), 74.6% (373/500), 5.4% (291/5,341), 78.0% (291/373), 0.34% (18/5,341), and 0.38% (17/4,428), respectively. Of 20,458 subjects who underwent TCS (mean age 57.1 ± 10.3), the colorectal tumor detection rate, cancer detection rate, and detection rate for first examination were 4.8% (987/20,458), 0.26% (53/20,458), and 0.31% (34/11,129), respectively. In the evaluation of screening for extracolonic lesions by CTC, the recall rate, consultation rate, and detection rate of high-risk lesions were 0.75% (40/5,341), 75.0% (30/40), and 0.17% (9/5,341), respectively. The high risk lesions detected were one case of lung cancer, one of pancreatic cancer, one of follicular lymphoma, three cases of intraductal papillary mucinous neoplasia of pancreas, one of mucinous cystic neoplasia of pancreas, and two cases of abdominal aortic aneurysm.
Conclusion: The use of CTC for opportunistic screening may be feasible because its diagnostic accuracy for primary colorectal cancer was equivalent to that of TCS. Although the rate of detecting clinically significant extracolonic lesions using CTC was very low, we should still use it to evaluate such lesions because serious diseases were found.
