High yield of synchronous lesions in referred patients with large lateral spreading colorectal tumors.

BACKGROUND AND AIMS: There are few data on the prevalence of synchronous colorectal lesions in patients who have large lateral spreading tumors (LLSTs). We sought to describe the rate of synchronous lesions found in patients who underwent endoscopic resection of large sessile adenomas and serrated lesions. METHODS: This is a retrospective assessment of a prospectively created database of 728 consecutive patients with resected LLSTs who underwent complete clearing of the colon during 2 colonoscopies by a single expert endoscopist. RESULTS: The 728 patients with resected LLSTs and complete clearing had 4578 synchronous lesions, including 584 patients (80.2%) with at least 1 synchronous conventional adenoma, 132 (18.1%) with at least 1 synchronous conventional adenoma ≥ 20 mm in size, 294 (40.4%) with at least 1 synchronous advanced conventional adenoma, and 6 patients with a synchronous lesion with cancer. Patients with an index large sessile conventional adenoma compared with those with an index large serrated lesion had on average more synchronous conventional adenomas (4.8 vs 2.9, P = .001) and fewer synchronous serrated lesions (1.4 vs 4.5, P < .001). Of the 97 patients with a serrated class index lesion, 28 (28.9%) met criteria for serrated polyposis. CONCLUSIONS: There is a very high prevalence of synchronous lesions, including other large and advanced synchronous lesions, in patients with flat or sessile conventional adenomas and serrated colorectal polyps. Patients with LLSTs in the colon need detailed clearing of the rest of the colon. Patients referred for endoscopic resection of serrated lesions ≥ 20 mm have a very high prevalence of serrated polyposis. This study has potential implications for further stratification of high-risk patient groups in postpolypectomy surveillance guidelines.