Factors for conversion risk of colorectal endoscopic submucosal dissection: a multicenter study.

BACKGROUND: Endoscopic submucosal dissection (ESD) has become a widely accepted treatment method for colorectal tumors; however, there are some persistent problems. This multi-center study aimed to characterize the risk factors for incomplete resection and perforation in standardized colorectal ESD procedures. METHODS: This study included 2423 consecutive patients who underwent ESD for 2592 colorectal tumors between August 2013 and December 2018 at 11 institutions (1 academic hospital and 10 affiliated hospitals) from the Hiroshima GI Endoscopy Research Group. We evaluated the risk factors for interruption, piecemeal resection, and perforation of standardized colorectal ESD in relation to clinicopathologic and endoscopic characteristics. RESULTS: The incidences of interruption, piecemeal resection, and perforation were 0.7%, 2.9%, and 3.0%, respectively. Multivariate analysis identified the following risk factors for interruption: perforation during the procedure, deep submucosal invasion (> 1000 mum), poor scope operability, and severe submucosal fibrosis. The risk factors for piecemeal resection included poor scope operability, severe submucosal fibrosis, and procedure time (>/= 85 min). The risk factors for perforation during the procedure were severe submucosal fibrosis, poor scope operability, procedure time (>/= 85 min), and tumor size (>/= 40 mm). Independent risk factors for severe submucosal fibrosis included a history of biopsy and lesions located on the fold or flexure. CONCLUSIONS: Severe submucosal fibrosis and poor scope operability are the common risk factors for interruption, piecemeal resection, and perforation in standardized colorectal ESD.