Five-year evaluation of Anal Cancer Screening Program in Men Who Have Sex With Men with HIV at Two Academic Center Clinics.

Background: Guidelines recommend annual anal cytology-based squamous cell carcinoma of anus (SCCA) screening for men who have sex with men (MSM) with HIV aged ≥35 years (eligible population). Recommended threshold for high resolution anoscopy (HRA) depends on its availability: low-threshold (any abnormal cytology) if availability is high, and high-threshold (High-Grade Squamous Intraepithelial Lesion (HSIL) on cytology) if availability is low.

Methods: Retrospective chart review (2018-2022) at academic HIV clinics. We evaluate (i) 5-year uptake of cytology based SCCA screening in eligible population; (ii) estimate HSIL detection rate based on our current low-threshold criteria, and if high-threshold criteria were used for HRA referral.

Results: Of 432 eligible individuals, only 219 (50.7%) had at least one, and only 113 (26%) had >1 SCCA screening tests in a median followup of 4 years. N=74 (17.1%) of individuals had at least one abnormal anal cytology during follow-up, of which 56 (75.6%) received HRA. Increasing age (≥57 years) and history of smoking negatively correlated with ever receiving screening. Anal cytology (365 tests in 206 individuals) showed: 17.5% 'unsatisfactory', and 26.8% with any abnormal cytology (zero with HSIL) triggering HRA referral. Only 34 individuals (7.8% of screening eligible) were ever detected with HSIL. Strictly using high-threshold criterion for HRA referral would have led to no HRA or HSIL detection.

Conclusions: We noted poor uptake of screening over time, particularly in older age groups. Importantly, anal cytology performed poorly as a triage test for HRA referral: high rates of 'unsatisfactory' samples and low sensitivity for detecting HSIL.