Progression of low-grade dysplasia in ulcerative colitis: effect of colonic location

Background Emerging evidence suggests that the biology of sporadic colorectal neoplasia may differ between the proximal and distal colon. Whether such a difference exists in colitis-associated colorectal neoplasia is unknown. Objective To compare the rate of progression to advanced neoplasia (AN) between proximal and distal dysplasia in patients with ulcerative colitis (UC). Design Retrospective cohort study. Setting Tertiary medical center. Patients From an institutional database of more than 700 patients with UC who underwent 2 or more surveillance colonoscopies between 1994 and 2006, we identified patients with extensive UC and low-grade dysplasia (LGD). Neoplasia proximal to the splenic flexure was considered proximal. Main Outcome Measurement Progression to AN, defined as high-grade dysplasia (HGD) or colorectal cancer (CRC). Results Among 121 patients with LGD, all 7 who progressed to CRC and 6 of 8 who progressed to HGD had distal LGD initially. Subjects with distal LGD had a significantly shorter time to progression than those with proximal LGD ( P = .019); 5-year AN-free survivals for distal and proximal LGD were 75 ± 7% and 95 ± 3%, respectively (hazard ratio [HR] 5.0; 95% CI, 1.1-22.0). Additionally, flat LGD was significantly more likely to progress than raised LGD on univariate testing (HR 3.6; 95% CI, 1.3-10.1). Neither morphology nor sidedness remained significant in multivariable testing, although there was little change in the HRs (HR 2.4; 95% CI, 0.8-7.1 for morphology; HR 3.5; 95% CI, 0.7-16.8 for sidedness) in proportional hazards modeling. Limitations Nonrandomized, retrospective trial and low incidence of AN. Conclusions In patients with long-standing, extensive UC, distal LGD is more common and progresses more rapidly to AN than proximal LGD.