Learning curve of pocket-creation method-assisted colorectal endoscopic submucosal dissection: a single-operator retrospective observational study from South Korea using cumulative sum analysis.

BACKGROUND/AIMS: Colorectal endoscopic submucosal dissection (C-ESD) is a technically demanding procedure with an extended learning curve. We aimed to characterize the learning process after introduction of the pocket-creation method (PCM) and provide practical guidance for endoscopists. METHODS: We retrospectively analyzed 147 colorectal lesions treated with PCM-assisted C-ESD. Learning curves for dissection speed and procedure time were evaluated using locally weighted regression. Cumulative sum (CUSUM) analysis was used to identify the point of technical stabilization, with a predefined acceptable failure rate of 10%. Outcomes were compared between the pre- and post-stabilization phases, and multivariate logistic regression was used to identify the predictors of technical failure. RESULTS: Dissection speed increased and procedure time decreased with experience. CUSUM analysis identified stabilization at 60 cases. Compared with the post-stabilization phase, the pre-stabilization phase showed higher technical failure rates and lower en bloc and R0 resection rates. The learning phase was the only independent predictor of technical failure. Perforation occurred in 5.4% of cases and was managed predominantly endoscopically. CONCLUSIONS: PCM-assisted C-ESD showed a distinct learning curve, with stabilization achieved after 60 cases. Technical failure is primarily driven by operator experience rather than by lesion complexity.