Technique, sedation, and clinical outcome of endoscopic submucosal dissection for rectal tumor with involvement of dentate line: A retrospective cohort study.

Background: Endoscopic submucosal dissection (ESD) of rectal tumors involving the dentate line (RT-DL) is challenging because of the anatomical features of the anal canal. This study aimed to identify optimal techniques and sedation and to determine the clinical outcomes of ESD for RT-DL. Methods: We retrospectively collected medical records and endoscopic results of patients who underwent ESD for rectal tumors between January 2012 and April 2021. Patients were divided into RT-DL and rectal tumors not involving the dentate line (RT-NDL) groups, as per involvement of the dentate line. The treatment results and clinical outcomes of the two groups were evaluated and analyzed. Additionally, subgroup analysis was performed in the RT-DL group for the sedation method involved. Results: In total, 225 patients were enrolled and 22 were assigned to the RT-DL group. The complete resection rate (90.9% vs. 95.6%, P =0.336), delayed bleeding (13.6% vs. 5.9%, P =0.084), perforation (0% vs. 3.9%, P = 0.343), hospital stays (4.55 vs. 4.48 days, P = 0.869), and recurrence (0% vs. 0.5%) showed no significant group differences. However, in RT-DL group, the procedure time (78.32 vs. 51.10 min, P = 0.002) was longer and there was more perianal pain (22.7% vs. 0%, P = 0.001). The subgroup analysis revealed that deep sedation using propofol reduced perianal pain during the procedure (0/14 vs. 5/8, P = 0.002). Conclusions: ESD of RT-DL is a safe and effective treatment despite the challenges of requiring a high level of technique and longer procedure time. In particular, ESD under deep sedation should be considered in patients with RT-DL to control perianal pain.