Nearly a Third of High-Grade Dysplasia and Colorectal Cancer Is Undetected in Patients with Inflammatory Bowel Disease.

<bold>Background: </bold>It is unclear whether intensive surveillance protocols have resulted in a decreased incidence of colorectal cancer (CRC) in inflammatory bowel disease (IBD).<bold>Aims: </bold>To determine the prevalence and characteristics of IBD associated high-grade dysplasia (HGD) or CRC that was undetected on prior colonoscopy.<bold>Methods: </bold>This is a single-center, retrospective study from 1994 to 2013. All participants had a confirmed IBD diagnosis and underwent a colectomy with either HGD or CRC found in the colectomy specimen.The undetected group had no HGD or CRC on prior colonoscopies. The detected group had HGD or CRC identified on previous biopsies.<bold>Results: </bold>Of 70 participants, with ulcerative colitis (UC) (n = 47), Crohn's disease (CD) (n = 21), and indeterminate colitis (n = 2), 29% (n = 20) had undetected HGD/CRC at colectomy (15 HGD and 5 CRC). In the undetected group, 75% had prior LGD, 15% had indefinite dysplasia, and 10% had no dysplasia (HGD was found in colonic strictures). Patients in the undetected group were more likely to have pancolitis (55 vs. 20%) and multifocal dysplasia (35 vs. 8%). The undetected group was less likely to have CRC at colectomy (25 vs. 62%). There was a trend toward right-sided HGD/CRC at colectomy (40 vs. 20%; p = 0.08). In addition, 84% of the lesions found in the rectum at colectomy were not seen on prior colonoscopy in the undetected group.<bold>Conclusions: </bold>The prevalence of previously undetected HGD/CRC in IBD found at colectomy was 29%. The high proportion of undetected rectal and right-sided HGD/CRC suggests that these areas may need greater attention during surveillance. [ABSTRACT FROM AUTHOR]