Long-term Risk of Advanced Neoplasia After Colonic Low-grade Dysplasia in Patients With Inflammatory Bowel Disease: A Nationwide Cohort Study

BACKGROUND AND AIMS: The long-term risk of high-grade dysplasia HGD and colorectal cancer CRC following low-grade dysplasia LGD in inflammatory bowel disease IBD patients is relatively unknown. We aimed to determine the long-term cumulative incidence of advanced neoplasia HGD and/or CRC, and to identify risk factors for advanced neoplasia in a nationwide IBD cohort with a history of LGD. METHODS: This is a nationwide cohort study using data from the Dutch National Pathology Registry PALGA to identify all IBD patients with LGD between 1991 and 2010 in the Netherlands. Follow-up data were collected until January 2016. We determined the cumulative incidence of advanced neoplasia and identified risk factors via multivariable Cox regression analysis. RESULTS: We identified 4284 patients with colonic LGD with a median follow-up of 6.4 years after initial LGD diagnosis. The cumulative incidence of subsequent advanced neoplasia was 3.6, 8.5, 14.4 and 21.7%, after 1, 5, 10 and 15 years, respectively. The median time to develop advanced neoplasia after LGD was 3.6 years. Older age ≥ 55 years at moment of LGD (hazard ratio HR 1.73, 95% confidence interval CI 1.44-2.06), male sex HR 1.33, 95% CI 1.10-1.60, and follow-up at an academic vs non-academic medical centre HR 1.37, 95% CI 1.07-1.76 were independent risk factors for advanced neoplasia following LGD. CONCLUSIONS: In a large nationwide cohort with long-term follow-up of IBD patients with LGD, the cumulative incidence of advanced neoplasia was 21.7% after 15 years. Older age at LGD ≥55 years, male sex and follow-up by a tertiary IBD referral centre were independent risk factors for advanced neoplasia development after initial LGD.