Safety, feasibility, and short-term-outcome of anal endoscopic submucosal dissection for anal intraepithelial neoplasia: an option for focal lesions?

Background: Anal intraepithelial neoplasia (AIN) appears in three different stages. AIN 1 and AIN 2 (p16 negative) are defined as low risk and unlikely to progress to invasive anal cancer. AIN 2 (p16 positive) and AIN 3 are of high risk and should be treated because progression rates to anal cancer are around 10% and treatment significantly reduces this risk. The correct treatment is still a matter of debate. Human papilloma virus (HPV) plays a role in the development of AIN. Our aim was to assess anal endoscopic dissection (aESD) as an intervention for AIN3.

Methods: We retrospectively evaluated patients who underwent aESD for AIN 3 between December 2017 and March 2023. The interventional technique itself (duration, complications, size of specimen) and patient outcomes (recurrence, progression to anal cancer, re-intervention) were analyzed.

Results: Fifteen patients with a median age of 52 years (23-78) underwent aESD for AIN 3. All tested specimens were positive for HPV. Median duration of intervention was 56.1 min, one delayed postinterventional bleeding occurred, and specimen size was 12.05 cm. Median follow-up was 11.17 months. Three recurrences (20%) appeared: one was resected via biopsy and two were again treated with aESD. There was no progression to invasive anal cancer in the follow-up period.

Conclusions: Anal endoscopic submucosal dissection seems to be a safe and feasible treatment for AIN. Recurrences are seldom and can be treated again with the same method. Nevertheless, indications for resection in comparison to radiofrequency ablation, pharmacological therapy, and watch-and-wait strategy are still unclear.

Trial Registration: Ethics commission of Salzburg, Austria, EK-Nr. 1056/2023. Keywords: Endoscopic submucosal dissection, anal intraepithelial neoplasia, anal cancer.