Prospective study of the progression of low-grade dysplasia in ulcerative colitis using current cancer surveillance guidelines.

Background: The goal of this study was to assess the natural history of low-grade dysplasia (LGD) and its risk of progression in ulcerative colitis (UC) patients by prospective endoscopic surveillance.

Methods: Forty-two UC patients with LGD were followed prospectively using a uniform approach to surveillance colonoscopy with an average of 43 biopsies per exam. The interval between colonoscopies ranged from 3-12 months. Progression was defined as development of high-grade dysplasia (HGD) or cancer at subsequent colonoscopy or at colectomy. Univariate and multivariate analysis were performed to identify risk factors associated with progression.

Results: Patients were followed for an average of 3.9 years (range 1-13). Over that period 19% (8/42) of patients progressed to advanced neoplasia (two cancer, six HGD) while 17% (7/42) had persistent LGD and 64% (27/42) had indefinite dysplasia or no dysplasia at the end of follow-up. Multivariate analysis demonstrated that the number of biopsies with LGD at baseline was associated with an increased risk of progression to advanced neoplasia (relative risk [RR] 5.8, 95% confidence interval [CI]: (1.29-26.04). Among the 15 patients who underwent colectomy, four were found to have higher-grade neoplasia on their colectomy specimen than their preoperative colonoscopy, and these patients were more likely to be nonadherent with recommendations for colectomy.

Conclusions: The majority (81%) of UC patients with LGD did not progress to higher grades of dysplasia during a 4-year follow-up. Patients with three or more biopsies demonstrating LGD at a single colonoscopy were at increased risk for progression to advanced neoplasia.