P0182 - Prevalence of Dysplastic Sessile Serrated Lesions in a Large Colonoscopy Cohort in Australia

Lulu Zhang, MBBS, BSc¹, Nicholas Tutticci, MBBS, BSc¹, Mark Bettington, MBBS, BSc^2
1QEII Jubilee Hospital, Brisbane, Queensland, Australia; ²Envoi Specialist Pathologists, Brisbane, Queensland, Australia

Introduction: The serrated pathway accounts for 25% of colorectal cancers; however, sessile serrated lesions with dysplasia (SSL-Ds) are only encountered at colonoscopy in 0.5% of average-risk patients. There is significant heterogeneity in published SSL detection rates, and although pathologist and colonoscopist variability is well described, geographic variation in prevalence is also possible. Data on SSL-D prevalence in Australia is limited. We aim to present SSL-D prevalence in a large colonoscopy cohort with high detector colonoscopists.

Methods: A retrospective study was conducted using a prospective colonoscopy quality database of patients undergoing colonoscopy at a single center from January 2018 to December 2022. Univariate analysis (Wilcoxon Rank-Sum test and Pearson Chi-Square test) and multivariate analysis (multiple logistic regression) were performed.

Results: In 5 years, 21,903 colonoscopies were completed with 5,261 SSLs detected (24% detection rate). 70 SSL-Ds were identified at 62 colonoscopies (1.2% of procedures with SSL identified). SSL-D patients were older (median age 75 vs 58 years, p< 0.001) with a trend towards female association (67% vs 57%, p=0.09). SSL-Ds were more often found at surveillance colonoscopy than index (77% vs 23%). On multivariate analysis, only older age was an independent predictor of SSL-D (odds ratio 1.07, 95% confidence interval 1.05-1.1).

SSL-Ds were mainly found in the proximal colon (89%), with a mean size of 12mm (range 1 to 40mm) and were treated with cold snare (50%) or cold EMR (41%). 80% of SSL-Ds had surveillance at a median interval of 6 months. SSL-D residuals were encountered in only 4 (5.7% of total SSL-D). These returned bland on histology and cured with repeat cold snare resection, though one required cecumectomy due to location. Serrated polyposis syndrome was diagnosed in 21.4% of SSL-D patients.

Discussion: We present one of Australia’s largest colonoscopy-based SSL-D cohorts. SSL-Ds were more common on surveillance, which is a reminder to colonoscopists to remain vigilant, although multivariant analysis suggests that this may be a surrogate marker for increasing age. Majority of SSL-Ds were successfully managed endoscopically with residual dysplasia detected in a minority of cases which were cured with repeat cold snare resection. A sole SSL-D residual was confirmed at the appendiceal orifice polyp which ultimately proceeded to cecumectomy. Overall, SSL-Ds are relatively uncommon even within a high SSL prevalence cohort in Australia.


Disclosures:


Lulu Zhang, MBBS, BSc¹, Nicholas Tutticci, MBBS, BSc¹, Mark Bettington, MBBS, BSc². P0182 - Prevalence of Dysplastic Sessile Serrated Lesions in a Large Colonoscopy Cohort in Australia, ACG 2023 Annual Scientific Meeting Abstracts. Vancouver, BC, Canada: American College of Gastroenterology.