Learning curve of colorectal endoscopic submucosal dissection of an endoscopist experienced hands-on training in Japan.

Background and aim: Colorectal endoscopic submucosal dissection is a technically demanding procedure with a steep learning curve. In Japan, the National Cancer Center Hospital allows overseas doctors to participate in hands-on training. We aimed to assess the colorectal endoscopic submucosal dissection performance and learning curve of an endoscopist who participated in hands-on training.

Methods: In this retrospective analysis using a prospectively collected database, 100 consecutive superficial colorectal tumors from 100 patients treated with endoscopic submucosal dissection by a colorectal surgeon between January 2020 and May 2024 were included. The cases were grouped into three learning periods: phase I (the initial 30 cases under local expert supervision before training in Japan), phase II (the middle 30 cases), and phase III (the last 40 cases). The primary outcome was resection speed.

Results: The median resection speed was 5, 11.7, and 13.2 cm²/h in phases I, II, and III, respectively. In matched data, the resection speeds in phases II and III were higher than that in phase I (P = 0.02 and P < 0.001, respectively). En bloc and R0 resection rates were 99% and 95%, respectively. The en bloc resection, R0 resection, and complication rates were not different between phases. Cumulative sum analysis of the resection speed revealed that proficiency was achieved after 36 cases.

Conclusions: An endoscopist who underwent a tutored approach and hands-on training in Japan achieved the proficiency benchmarks for colorectal endoscopic submucosal dissection after 36 cases. However, the endoscopist's extensive experience before training may contribute to excellent outcomes.