Learning curve for mastery of colorectal endoscopic submucosal dissection: Perspectives from a large Japanese cohort

Background and Aim: Endoscopic submucosal dissection (ESD) is a challenging procedure. A dissection speed of ≥9 cm²/h has been acknowledged as a mark for expertise, alongside a complication rate of ≤5% and en bloc resection rate of ≥90%. However, there is lack of objective information on whether the three measures correlate with each other. This study aims to evaluate the dissection speed, safety, and efficacy of colorectal ESDs performed by experts and trainees. Methods: Consecutive patients undergoing colorectal ESD at a Japanese hospital (2006–2017) were included in a prospectively collected database. Information on patient demographics, proceduralist, and intra-/postprocedure data was retrieved. The primary outcome was the comparison in dissection speed. The secondary outcomes included differences in safety and efficacy. Log-linear regression models adjusted for confounders (e.g. R0 resection) were used to assess the differences in dissection speed. Results: Five hundred ninety procedures (514 patients) performed by 26 endoscopists were analyzed. Experts performed a higher number of difficult lesions (e.g. F2 fibrosis) but achieved higher dissection speed (10.3 vs 6.7 cm²/h). The difference was statistically significant for both unadjusted and adjusted models (P < 0.0001). The en bloc resection rates were similar for both groups (experts = 95.6%; trainees = 94.7%, P = 0.61). Although nonexperts damaged more of the muscularis propria (18.6 vs 12.5%, P = 0.04), this did not translate into a significant difference in perforation (experts = 3.7%; trainees = 6.9%, P = 0.09) or delayed bleeding (experts = 2.9%; trainees = 4.4%, P = 0.34). The dissection speed steadily increased with expertise. Conclusion: Although dissection speed for colorectal ESD was significantly higher for experts, ESDs could be safely and efficaciously performed by ESD trainees.