CT colonography after a positive faecal occult blood test in colorectal cancer screening in Japan.

Background and Aims: The purpose of this study was to estimate the sensitivity and specificity of CT colonography (CTC) for colorectal cancer screening following positive fecal occult blood test (FOBT) in Japan. Methods: This study included 183 patients with positive result of FOBT in Japanese colorectal cancer screening program. All patients had both CTC and TCS on the same day. We compared the results of CTC and TCS. Target lesions were colorectal polyp (>6mm) and tumor. Each CTC was read independently by two experienced observers by 3D primary reading methods. Per patient and lesion sensitivity, specificity, positive and negative predictive values (PPV, NPV) were calculated. Results: 96 patients (53%) had colorectal lesions, on the other hand 87 patients had no lesions. The total number of lesions was 191,including 77 lesions 6 mm in maximum diameter and larger, including 46 lesions 10 mm and larger. Colorectal cancer was 25 lesions (13%), including cancer in adenoma was 16 lesions (8%). Per lesion (>6mm) sensitivity for CTC was 83.2%. Per lesion (>10mm) sensitivity for CTC was 96%. All examination has never occurred in side effects. Conclusion:CTC has reasonable predictive values in FOBT positive population and a high acceptability to patients. However, to accept for Japanese colorectal cancer program, it has been some problems.