Anal Cancer Screening: 10-Year Experience of a Specialized Outpatient Clinic.

In 2012, the Department of Visceral Surgery of the Lausanne University Hospital CHUV implemented a dedicated high-resolution anoscopy (HRA) outpatient clinic for surveillance and follow-up purposes. This 10-year longitudinal study analyzed 537 patients (2214 visits) using a structured screening protocol. Dysplastic lesions were detected in 49% of patients, predominantly low-grade squamous intraepithelial lesions (LSILs, 74%). Among LSIL cases, 6% progressed to high-grade squamous intraepithelial lesions (HSILs) within 24 months, reaching 25% cumulative progression at 36 months. Of HSIL patients, 3% developed carcinoma in situ after 48 months. Notably, no invasive carcinoma was observed during the follow-up. Four patients diagnosed with squamous cell carcinoma at initial screening were treated with chemoradiotherapy, and one required salvage surgery. Independent risk factors for the presence of higher-stage precancerous lesions (≥HSILs) were the presence of high-risk HPV genotypes (OR 14.5, 95% CI 5-42.2, p < 0.001), detectable HIV viral load (OR 5.4, 95% CI 1.8-16.7, p = 0.003), and symptoms at the first screening visit (OR 3.2, 95% CI 1.1-9.9, p = 0.04). HIV-positive status was associated with a trend towards an increased risk of progression (OR 2.79, p = 0.073). These findings highlight the importance of systematic follow-up and early intervention in high-risk populations to prevent anal cancer progression.