Genotyping and Cytology Co-Testing for Anal Cancer Screening: Exploratory Evaluation of Cumulative HPV Genotype Burden as a New Potential Marker for Risk Stratification

Background/Objectives: Anal squamous cell carcinoma (SCCA) is a rare Human Papillomavirus (HPV)-related disease in the general population but its incidence is increasing among high-risk populations, i.e., men who have sex with men (MSM), HIV+ patients and women with a history of cervical/vulvar dysplasia. The objectives of this study were: (i) to investigate the prevalence of high-risk (HR) and low-risk (LR) anal HPV infections in a high-risk cohort; (ii) to correlate specific HPV genotypes with cytological and histological outcomes; and (iii) to assess the impact of cumulative HPV genotype burden. Methods: A retrospective study (2017–2022) was conducted on 550 high-risk patients. All patients underwent anal Pap tests (ThinPrep, Hologic) and HPV genotyping (Anyplex II HPV 28, Seegene), according to our screening protocol. High-Resolution Anoscopy (HRA) was performed on 430 patients; biopsy was performed in all cases with suspicious lesions. Results: The overall HR-HPV prevalence was 57.3%. Men showed a significantly higher prevalence of HR-HPV (59.9% vs. 47.4%) and cytological abnormalities (35.8% vs. 20.2%) compared to women. Notably, HPV 16, 58 and 45 accounted for 79% of AIN2+ (Anal Intraepithelial Neoplasia of grade 2 or higher) lesions. A significant cumulative HPV genotype burden effect, i.e., the number of HPV genotypes detected, was observed: patients with ≥3 HR-HPV types showed an increased risk of AIN2+ lesions (aOR 34.72; 95% CI 4.07–296.10) and AIN1+ lesions (aOR 16.26; 95% CI 4.54–58.30) respectively. The presence of ≥3 LR-HPV genotypes in HR-HPV-positive patients is associated with an increased risk of AIN1 lesions. Conclusions: HPV 16, 58 and 45 positivity and the cumulative HPV genotype burden could represent new potential indicators for risk stratification in high-risk populations. Future larger-scale prospective studies are needed to validate these preliminary results.