Anal Cancer Screening in People Living with HIV: A Pilot Study of Primary HPV Screening with Triage Use of p16/Ki67 Dual Stain.

Abstract

Background: and setting: People living with HIV (PLHIV), especially gay, bisexual, and other men who have sex with men (GBM), are at increased risk of anal cancer. A recent randomised controlled trial showed treating anal high-grade squamous intraepithelial lesions (HSIL) reduces anal cancer incidence, supporting development of screening programs. Given the transition from cytological to HPV testing in cervical cancer screening, HPV testing for anal cancer is worth investigating. However, due to its low specificity, additional biomarkers like the p16/Ki67 dual stain may improve specificity.

Methods: In this multicentre pilot study, PLHIV aged 35+ were recruited from sexual health centres and a general practice. Participants underwent digital anorectal examination (DARE) and anal swab collection for HPV and p16/Ki67 dual stain testing. High-resolution anoscopy (HRA) referrals were based on screening results at baseline and 12 months, with immediate HRA referral for HPV16-positive participants. The primary objective was to assess adherence to the screening program.

Results: From October 2019 to July 2021, 136 participants (median age 54) were recruited. Overall, 85.3% completed all screening and HRA steps, with 92.8% attending HRA referrals. At baseline, 71.4% had anal high-risk HPV (HRHPV), with 40 testing positive for HPV16. Of those with HRHPV, 42.1% had a positive p16/Ki67 dual stain, while 37.9% had unsatisfactory results. Among 37 HRA attendees, 73.0% had composite cytological/histological HSIL. At 12 months, 81.4% tested positive for HRHPV, and 25.9% had composite HSIL.

Conclusions: Adherence to the screening algorithm was 85.3%, with >90% attendance at HRA referrals. Screening identified composite HSIL in 53.1% of participants. Utility of the p16/Ki67 dual stain remains undetermined due to high rates of unsatisfactory samples.