Treatment outcomes of endoscopic submucosal dissection for lesions adjacent to the dentate line: a post hoc analysis from the Hiroshima GI Endoscopy Research Group Study.

INTRODUCTION: Endoscopic submucosal dissection (ESD) of rectal lesions adjacent to the dentate line is technically challenging. This study aimed to evaluate the short- and long-term outcomes of ESD for these lesions, identify factors associated with prolonged procedure time, and assess optimal device selection to increase dissection speed. METHODS: From a prospective multicenter observational study conducted by the Hiroshima GI Endoscopy Research Group, lesions adjacent to the dentate line resected using ESD were recruited. Treatment outcomes and those stratified by the presence of hemorrhoids and the degree of circumferential involvement were evaluated. Factors associated with prolonged procedure time were analyzed using multivariate analysis. Optimal device selection for achieving faster dissection speed was investigated using decision tree analysis. RESULTS: Seventy-three lesions were enrolled. Overall en bloc and complete resection rates were 97.2% and 90.4%, respectively, which were not associated with the presence of hemorrhoids or circumferential involvement. No local recurrence occurred with a median follow-up of 40 months. Larger tumor size and severe intraoperative bleeding were significant predictors of prolonged procedure time. Decision tree analysis demonstrated higher dissection speed with the ITknife nano (Olympus) or SB Knife Jr (Sumitomo Bakelite) than with the DualKnife J (Olympus) for lesions ≥30 mm. For lesions measuring ≥20 mm and <30 mm with hemorrhoids, the ITknife nano achieved the highest dissection speed. CONCLUSION: ESD for rectal lesions adjacent to the dentate line yields favorable short- and long-term outcomes. Although large lesions and intraoperative bleeding prolong procedure time, appropriate device selection can mitigate these challenges.