S3111 Metachronous Advanced Serrated Polyps in Post-Polypectomy Patients

Abstract

INTRODUCTION: Clinically significant serrated polyps (SPs) including sessile serrated adenomas (SSAs), traditional serrated adenomas (TSAs) and hyperplastic polyps ≥ 10 mm have been shown to rapidly progress to colorectal cancer. Advanced serrated polyps (ASPs) include SSAs ≥ 10 mm, SSAs with cytological dysplasia, hyperplastic polyps ≥ 10 mm and TSAs of any size. The incidence and risk factors of metachronous ASPs are not well described and may affect surveillance guidelines. METHODS: We performed retrospective analysis of post-polypectomy patients ≥ 50 years old who received index and follow-up colonoscopy between January 2014 and December 2018 at a single tertiary centre. Exclusion criteria were applied, and the following data was collected: demographics, conventional adenoma characteristics, SP characteristics and adenoma multiplicity (≥3 adenomas). RESULTS: A total of 969 patients had at least one adenoma removed at index colonoscopy. Patients had a mean age of 65.4 years and a mean time of 23.9 months between colonoscopies. At index colonoscopy, SPs, TSAs and cytological dysplasia was seen in 37.3%, 1.8% and 0.7% of patients respectively. The incidence of metachronous SP and ASP was 20.3% and 4.0% respectively. On multivariate analysis, significant predictors of metachronous ASP included age 70–74 years, presence of a SP and SPs ≥ 10 mm (Table 1). CONCLUSION: The incidence of metachronous SP and ASP over a 23.9-month follow-up period was 20.3% and 4.0% respectively. Patients are at increased risk for metachronous ASP if they are aged 70-74yrs, have a SP or have a SP ≥ 10 mm.Table 1Keywords: metachronous advanced serrated polyps, incidence, risk