Introduction

Endoscopic submucosal dissection (ESD) is a valuable technique for the en-bloc resection of superficial neoplasms in the anal canal. However, its safety and efficacy in patients who have previously undergone transanal endoscopic surgery (TES) —such as transanal minimally invasive surgery (TAMIS) and transanal endoscopic microsurgery (TEM)—remain unclear.

Aims & Methods

To assess the safety and outcomes of ESD in the anal canal for patients with a history of TES compared to naïve patients.
A retrospective analysis was conducted at our tertiary center on 51 patients who underwent ESD in the anal canal between March 2010 and November 2024. Patients with a history of transanal endoscopic surgery were compared to those undergoing ESD as their primary treatment. Key parameters, including resection speed, perforation rates, coagrasper usage, inpatient status, late hemorrhage, and recurrence, were evaluated. Statistical analysis was performed to determine significant differences between groups.

Results

Histological examination confirmed the following cases: 3 adenocarcinomas (including 1 non-curative ESD), 15 adenomas with high-grade dysplasia, 11 adenomas with low-grade dysplasia, 2 sessile serrated lesions, 15 sessile serrated lesions with dysplasia, 2 high-grade intraepithelial lesions, 2 low-grade intraepithelial lesions.
The median resection velocity was slightly lower in patients with recurrence (16.01 mm²/min) compared to those without recurrence (25.56 mm²/min), though this difference did not reach statistical significance (p = 0.062). Perforation occurred in 9.62% of cases, with similar rates between groups (p = 0.58), suggesting that prior TEM does not significantly increase the risk of this complication. Late hemorrhage was observed in 7.84% of patients, again without a significant difference between groups (p = 0.29).
The only statistically significant finding was the smaller lesion size in patients with recurrence (1,162 mm² vs. 2,250 mm², p = 0.045). This is likely due to intensive post-TEM surveillance, which allowed for early detection of recurrence before lesions could grow larger. Other factors, including sex, age, use of coagrasper during the procedure, en-bloc resection, R0 status, and inpatient admission rates, showed no significant differences between groups.

Conclusion

ESD in the anal canal after prior TES appears to be a safe and feasible procedure, with outcomes statistically comparable to those in naïve patients. Although absolute numbers suggest differences, particularly in lesion size, these findings may be influenced by the small sample size. Larger studies are needed to confirm these results and further evaluate long-term efficacy.