Optimising colorectal cancer surveillance in inflammatory bowel disease

Inflammatory bowel disease (IBD), comprising ulcerative colitis and Crohn’s disease, is a chronic inflammatory condition of the gastrointestinal tract. Compared with the general population, patients with colonic IBD are at increased risk of developing colorectal cancer (CRC). Because of this increased risk patients are enrolled into colonoscopic surveillance programs, to allow for early detection and treatment of dysplasia and CRC. The aim of the research described in this thesis is to optimise CRC surveillance in patients with IBD. More specifically, the main aims of this thesis include: 1. To improve risk stratification for (advanced) colorectal neoplasia (aCRN). 2. To evaluate the most effective colonoscopic colorectal neoplasia (CRN) detection method.

In a meta-analysis all known prognostic factors for advanced colorectal neoplasia (aCRN, high-grade dysplasia and CRC) were identified and their effect size was estimated. Next, a dynamic prediction model was developed and validated for aCRN risk in patients with IBD. Prognostic factors were included based on data from the meta-analysis. In the future the predicted aCRN risks can be related to surveillance intervals. To enable identification of patients’ preferences regarding CRC surveillance in IBD, a discrete choice experiment was conducted. The most important attribute was volume of bowel preparation, followed by surveillance interval and CRC risk reduction. Heterogeneity in preferences was explained by three subgroups: “surveillance avoidant”, “CRC risk avoidant”, and “surveillance preferring”. These findings provide insight in differing patients’ preferences.

Last, three colonoscopic surveillance techniques were compared on CRN detection rates in patients with IBD. The aim of this study was to distinguish between the impact of enhanced imaging in dye-based chromoendoscopy and the effect of re-inspection of colonic segments after dye spraying in the era of high-definition (HD) endoscopes. We found that HD-white light endoscopy (HD-WLE) with segmental re-inspection was non-inferior to HD-chromoendoscopy. HD-WLE with segmental re-inspection was not superior to single-pass HD-WLE. These results suggest that HD-WLE with segmental re-inspection could be a suitable alternative to HD-chromoendoscopy, with the potential benefit that uptake in daily clinic might be higher.