Surgical excision of anal intraepithelial neoplasia.

INTRODUCTION: Anal intraepithelial neoplasia (AIN) is a premalignant lesion caused by human papillomavirus. Surgical excision is the preferred treatment, but recurrence rates are high, and the risk of progression to squamous cell carcinoma of the anus (SCCA) remains. METHODS: This retrospective study included all patients with histologically confirmed AIN treated and/or followed at Herlev Hospital, Denmark, from 1 October 2021 to 30 September 2022. Standard treatment was surgical excision or electrocautery. Data on demographics, clinical characteristics, histology, recurrence, progression to SCCA and complications were collected. Median follow-up was 30 months. RESULTS: A total of 77 patients were included (median age 51 years; 80.5% female); 21% were infected with HIV and 9% were immunosuppressed. High-grade squamous intraepithelial lesions were present in 90.9% of primary resections. Recurrence occurred in 59.7%, with a median time to recurrence of nine months; female sex was significantly associated with recurrence (p = 0.037). Eight patients (10.4%) developed SCCA, mostly stage T1, with no nodal or distant metastases. No significant predictors of cancer development were identified. One patient (1.3%) experienced a severe surgical complication. CONCLUSIONS: AIN has a high recurrence rate after excision and a notable risk of progression to SCCA. Early-stage detection supports the importance of structured long-term surveillance. FUNDING: None. TRIAL REGISTRATION: The study was a quality development study (WorkZone no.: 25007943).