Risk of Metachronous Findings After Detection of Serrated Lesions and High-grade Dysplasia With Surveillance Delay

The primary aim of this study is to determine the rate of total metachronous advanced neoplasia (TMAN) detection after index detection of serrated lesions (SL) \[sessile serrated polyps (SSPs), traditional serrated adenomas (TSAs)\], and metachronous high-risk adenoma (HRA) after index detection of high-grade dysplasia (HGD). We will use the database of patients diagnosed with SL or HGD at index colonoscopy with a delay in surveillance and determine the risk of advanced lesions (especially high-risk lesion and CRC detection) of these delayed colonoscopies. The aim is to determine the effects of breach of continuity of care in these patients.

Inclusion Criteria: * Patients 45-80 who underwent colonoscopy from 2009 to 2022 at the Montreal University Hospital Center (CHUM) with 1+ SL or HGD detected at index colonoscopy and lacking follow-up within or beyond the surveillance interval recommended by 2020 USMSTF guidelines. Exclusion Criteria: * 1\) Patients with a diagnosis of inflammatory bowel disease; * 2\) Hereditary CRC syndromes; * 3\) CRC at index colonoscopy; * 4\) Serrated polyposis syndrome; * 5\) Life expectancy too short to benefit from colonoscopy; * 6\) Follow-up colonoscopy not yet due according to USMSTF guidelines. Patients with concomitant HRA and SL at index will be invited to participate if the index (or last) colonoscopy was performed more than 1 year ago. This is based on the high rates of HRA we identified in our retrospective study posing increased risks for these patients.