Retrospective analysis of pre- and peri-operative imaging in confirmed proximal colonic cancers--possible implications for screening flexible sigmoidoscopy.

Objective  Faecal occult blood testing is being introduced for population screening in the United Kingdom. Flexible sigmoidoscopy may provide a viable alternative. The outcomes of the flexible sigmoidoscopy trial are awaited but the most obvious disadvantage is that only the lower third of the colon is examined and proximal pathology cannot be excluded. The relationship between proximal pathology and distal findings at flexible sigmoidoscopy is uncertain. The aim of this study was to determine the incidence of distal neoplasia in patients with confirmed proximal cancers of the colon. Method  All confirmed proximal colonic cancers (defined as those proximal to the splenic flexure) were identified from a database of pathology specimens at a single centre between January 1999 and August 2006. A retrospective analysis of preoperative and peri-operative mucosal imaging (contrast enema, colonoscopy and CT colonography) was conducted to identify any distal neoplasia in these patients. Results  A total of 348 patients were identified. Pre- or peri-operative mucosal imaging was identified in 231 (66%) and 49 (21%) had distal neoplasia. Nineteen (8%) of these patients would have gone on to have a colonoscopy based on the UK flexible sigmoidoscopy trial protocol and 92% of the cohort would not have had a colonoscopy. Conclusion  Nearly 80% of confirmed proximal cancers in our series did not have any demonstrable distal neoplasia. Only 8% of our cohort would have proceeded to colonoscopy. A very significant number of proximal cancers would not have been detected.