Increased risk of high-grade dysplasia and colorectal cancer in inflammatory bowel disease patients with recurrent low-grade dysplasia

Background and Aims: The impact of recurrent low-grade dysplasia (LGD) on the risk of advanced neoplasia (high-grade dysplasia and colorectal cancer) in inflammatory bowel disease (IBD) patients is unknown. In addition, it is unclear how a neoplasia-free period after index LGD impacts this risk. We aimed to determine whether recurrent LGD is a risk factor for advanced neoplasia development and to evaluate the impact of a neoplasia-free time period after initial LGD diagnosis on the advanced neoplasia risk. Methods: This is a nationwide cohort study using data from the Dutch National Pathology Registry to identify all IBD patients with LGD and ≥1 follow-up colonoscopy between 1991 and 2010 in the Netherlands. Follow-up data were collected until January 2016. We compared the cumulative advanced neoplasia incidence between patients with and without recurrent LGD at first follow-up colonoscopy using log-rank analysis. We subsequently studied the impact of a neoplasia-free period after initial LGD on the advanced neoplasia incidence. Results: We identified 4284 IBD patients with colonic LGD with a median follow-up of 6.4 years. Recurrent LGD was a risk factor for advanced neoplasia (hazard ratio, 1.66; 95% confidence interval, 1.22-2.25; P = .001). A neoplasia-free period of at least 3 years after LGD protected against advanced neoplasia. Conclusions: Recurrent LGD at follow-up colonoscopy after initial LGD was a risk factor for advanced neoplasia. A neoplasia-free period of at least 3 years after initial LGD was associated with a reduced subsequent risk of advanced neoplasia.