Meta-analysis: cancer risk of low-grade dysplasia in chronic ulcerative colitis

Background The cancer risk of low-grade dysplasia (LGD) in chronic ulcerative colitis is variable and its management remain contentious. Aim To determine the risk of cancer or any advanced lesion once LGD is diagnosed. Methods A MEDLINE, EMBASE and Pub Med search was conducted using the key words 'surveillance', 'colorectal cancer', 'low-grade dysplasia' and 'ulcerative colitis'. A random effects model of meta-analysis was used. Results Twenty surveillance studies had 508 flat LGD or LGD with dysplasia-associated lesion or mass. An average of 4.3 colonoscopies was performed/patient post-LGD diagnosis (range: 3-7.6). An average of 18 biopsies taken per colonoscopy (range: 9-24) detected 73 advanced lesions (cancer or high-grade dysplasia) pre-operatively. The cancer incidence was 14 of 1000 (95% CI: 5.0-34) person years duration (pyd) and the incidence of any advanced lesion was 30 of 1000 pyd (95% Cl: 12-76). When LGD is detected on surveillance there is a ninefold risk of developing cancer (OR: 9.0, 95% CI: 4.0-20.5) and 12-fold risk of developing any advanced lesion (OR: 11.9, 95% CI: 5.2-27). Conclusions The risk of developing cancer in patients with LGD is high. These estimates are valuable for decision-making when LGD is encountered on surveillance.