TP1.2.2CT Colonography (CTC) Should be the ‘Gold Standard’ in Suspected Colonic Malignancy: Results of a Retrospective Cohort Study

Abstract

Abstract Aim Colonoscopy is the ‘gold’ standard with CT Colonography (CTC) being an alternative to investigate symptoms of colorectal cancer (CRC). Colonoscopy is invasive and can be embarrassing and distressing for patients. This retrospective cohort study aimed to investigate the validity of CTC in patients with suspected CRC. Methods We retrospectively reviewed 815 electronic patient records for those undergoing CTC in a large teaching hospital, between 2013 and 2015. Demographic data in addition to specific data on indication for CTC, endoscopic evaluation and further radiological imaging was collected until 2018. Results Mean age of the cohort was 67 (21 - 93 years). 326 (40%) patients underwent lower GI endoscopy in the three months preceding CTC, whilst 90 (11%) patients underwent endoscopy in the year following CTC. 37 patients had a CT Colonography Reporting Data System score (C-RADS) of C4 suggesting a colonic malignancy. Of these 21 (57%) were confirmed CRC, others demonstrated benign pathology (32%) or were unit or lost to follow up (11%). 56 (7%) had C-RADS of E4 suggesting significant extracolonic findings, 6 (11%) of which were renal cell carcinomas. Only 2 patients went on to develop a colorectal malignancy within our follow up period. Conclusions This large retrospective cohort study demonstrates that CTC is a reliable and valid tool. The authors propose that CTC should be the first line investigation with endoscopy reserved for use as an adjunct for diagnosis.Despite the limitations of a retrospective review, we were able to generate large patient numbers in order to establish our outcomes.