P217 Rate of undetected dysplasia at colectomy in patients with IBD - What are we missing?

Abstract

Abstract Background Patients with Inflammatory Bowel Diseases (IBD) are at higher risk of developing dysplastic lesions and colorectal cancer (CRC). Despite the use of high-definition endoscopes, dysplasia is not always detected at colonoscopy. This study aims to determine the rate of dysplastic lesions detected only at colectomy in IBD patients and to identify the characteristics of patients with undetected dysplasia. Methods We retrospectively identified IBD patients that underwent total or sub-total colectomy at Mayo Clinic, between January 2013 and December 2022. Patients with a confirmed IBD diagnosis, with at least one colonoscopy report prior to surgery available, were included. Data collected was demographics, comorbid conditions, colonoscopy, surgery, and their pathology reports. Concordance between dysplasia found at colonoscopy and dysplasia found at surgery was evaluated, noting dysplasia sites and grade. Patients were then divided into three groups: those with at least one undetected dysplastic lesion at surgery, those with dysplasia detected at colonoscopy and no further lesions at surgery, and those without dysplasia at both. Results Seven hundred-four patients were included: 387 (55%) were male, 450 (64%) had ulcerative colitis, 197 (28%) had Crohn’s disease and 57 (8%) had indeterminate colitis. In 42 patients (6%) dysplasia was undetected at colonoscopy, 136 (19.3%) had dysplasia detected at colonoscopy, and 526 (74.7%) had no dysplasia at both. In the group with dysplasia detected, 40 patients (30%) had dysplasia only at colonoscopy while 96 (70%) had dysplasia at surgery as well. Among those with undetected dysplasia, in 17 (40%) dysplasia was identified only at surgery: 14 (82%) had low grade dysplasia and 3 (18%) had cancer. All cancers were stage 1. Three of these patients (18%) had primary sclerosing cholangitis and 4 (23%) had a family history of cancer. In the other 25 patients (60%), dysplasia was detected at colonoscopy but further dysplastic foci were identified at surgery. In 13 (52%) patients dysplasia was upgraded, in 2 (8%) was downgraded and in 10 (40%) the grade was confirmed. Compared to those with detected dysplasia, these patients more frequently had moderate-severe disease activity, and less frequently a prior history of dysplasia. There was no difference in age at surgery, but those with undetected dysplasia had less years of disease at colectomy. Further results are shown in Table 1. Conclusion The rate of dysplastic lesions found at colectomy and missed at colonoscopy is 6%. Dysplastic lesions tend to be undetected when endoscopic disease activity is more severe and regardless of the use of extensive nontargeted biopsies.