Real-world learning curve analysis of colorectal endoscopic submucosal dissection: a large multicenter study.

Background: The current status of colorectal endoscopic submucosal dissection (ESD) performed by endoscopists without colorectal ESD experience is unknown. This study evaluated the quality of colorectal ESD performed by endoscopists without colorectal ESD experience.

Methods: We retrospectively examined the outcomes of 420 consecutive patients with 427 superficial colorectal tumors (male/female, 251/169; mean age, 69 years) who underwent ESD. The procedures were performed by 31 endoscopists without colorectal ESD experience using needle knife-type devices at 13 hospitals from October 2008 to June 2017. Cases were divided into the first and second phases according to the experience of the endoscopist: the first phase included the first 20 cases and the second phase included case 21 and beyond. We also identified factors associated with en bloc resection failure.

Results: Rates of colonic tumors, laterally spreading tumors of the non-granular type, poor scope operability, and severe submucosal fibrosis for the first phase were significantly lower than those for the second phase. The en bloc resection rates for the first and second phases were 93% and 96%, respectively. The factors associated with en bloc resection failure were poor scope operability (odds ratio [OR] 2.6; 95% confidence interval [CI] 1.0-6.5), severe submucosal fibrosis (OR 6.5; 95% CI 2.6-15.9), and the first 20 cases (OR 3.4; 95% CI 1.2-10.1).

Conclusion: Inexperienced endoscopists should initially perform colorectal ESD for tumors without severe submucosal fibrosis under good scope operability for at least 20 cases.