NORTH AMERICAN EXPERIENCE OF ENDOSCOPIC SUBMUCOSAL DISSECTION OF DISTAL RECTAL LESIONS EXTENDING TO THE DENTATE LINE - A LARGE SCALE MULTICENTER STUDY

Introduction:
Resection of distal rectal lesions extending to the dentate line is technically challenging due to unique anatomical features and the ideal treatment strategy remains unclear. Compared to transanal surgery where the devices and maneuverability are limited by anatomy and stabilization, Endoscopic Submucosal Dissection (ESD) has shown to be feasible and safe based on case series originating from Asian and European centers, though data regarding its use is scarce. We aim to evaluate the safety and efficacy of ESD for resection of distal rectal lesions within 2 cm of the dentate line in the United States (US) population.

Methods:
This was a multicenter retrospective study of patients who underwent ESD for resection of distal rectal lesions located within 2 cm of the dentate line between 2015 and 2023. The primary outcomes were the rate of R0 resection and en bloc resection. Secondary outcomes were adverse events including immediate and delayed bleeding, full-thickness wall injury, pain, strictures, procedure-related emergency department (ED) visits, and need for hospitalization.

Results:
A total of 257 patients across 20 institutions were included. 48.2% of the patients were female and the mean age was 63.5 years [Table 1]. The mean lesion size was 43.5 mm and the mean resection time was 132.5 minutes. Lesion and procedure characteristics are summarized in Table 2. The rate of R0 resection was 85.4% (n=216) and en bloc resection rate was 93.7% (n=236). There were no significant differences in R0 resection and en bloc resection rates based on lesion size. The rate of overall adverse events was 8.2% (n=21). The rate of delayed bleeding was 4.3% (n=11). Among these patients, one patient required a blood transfusion. There were four cases of full-thickness wall injury and one case of postinterventional pain requiring intervention. There were no cases of immediate bleeding and stricture. Six patients visited the ED due to procedure-related complaints. 47 out of 52 (90.4%) patients who were hospitalized after the procedure were for observation only as considered appropriate by the endoscopists. Endoscopic follow-up showed no evidence of residual or recurrent tumor when reported.

Conclusion:
Based on our data, ESD is safe and effective for resection of distal rectal lesions within 2 cm of the dentate line with a high rate of en bloc and R0 resection. ESD may offer an excellent option for distal rectal lesions where transanal surgery has technical limitations. The inclusion of multiple centers across the US increases the generalizability of our results despite minor variations in endoscopists’ experience and technique. Randomized controlled trials comparing ESD with transanal surgery are warranted.