GS1 - Evaluation of Anal Cancer Screening Practices Among a National Cohort of Veterans with HIV

Purpose/Background: People with HIV are at high risk for anal squamous cell carcinoma (ASCC) and its treatable precursors (anal squamous intraepithelial lesions [ASIL]). Anal screenings to detect ASIL and ASCC are recommended annually for all veterans with HIV. However, barriers to anal screenings exist and contribute to underutilization. When available, cytologic evaluations (anal Pap smears) are part of initial anal screening whereas diagnostic histologic evaluations are performed after abnormal Paps or in those with initial symptomatic presentations. The primary objective of this study is to describe the initial pathologic evaluations performed in veterans with HIV by distinguishing between screening assessments with cytopathology and diagnostic assessments with histopathology. We also aim to compare demographic and clinical characteristics between these two groups and to evaluate trends in initial anal pathologic evaluations over time.

Methods/Interventions: This is a national retrospective cohort analysis of veterans with HIV who received VA care between 1999-2023. We collected demographic and clinical data on all patients and divided those with anal pathology into two groups based on their first-ever anal pathology evaluation in the VA: 1) screening assessment with cytopathology and 2) diagnostic assessment with histopathology. We identified negative, ASIL, and ASCC results by analyzing all anal cytopathology and histopathology reports. To assess temporal trends in initial anal pathologic evaluations, we calculated annual rates of first-ever pathologic evaluations. We compared categorical and continuous variables using Pearson’s chi-squared test and Welch’s t-test, respectively.

Results/Outcomes: We analyzed a total of 48,368 veterans with HIV. 7,127 (15%) patients had at least one anal pathology result. Initial pathologic assessments were cytopathology in 4,477 (63%) and histopathology in 2,650 (37%). Among patients with pathology results, the majority were male (98%) with a mean age of 51.8 years (SD=12.1) and a mean follow-up of 7.9 years (SD=5.0). Annual rates of first-ever anal pathologic evaluations were low throughout the study period. The average annual rate of first-ever pathologic evaluations was 1.04%. A decrease in anal evaluations was observed after 2020. Average rates of first-ever anal pathologic evaluations during the three years before and after 2020 were 1.16% and 0.76% (p=0.032). During these two time periods, proportions of cytopathology and histopathology remained stable (70% and 30% vs 69% and 31%, p=0.924) (Figure 1). Among the five geographic VA regions, the Pacific region had the highest proportion of cytopathologic evaluations compared with histopathologic evaluations (77%), and the Continental region had the lowest proportion of cytopathologic versus histopathologic evaluations (37%, p< 0.001). Conversely, the lowest and highest rates of ASCC were observed in the Pacific and Continental regions, respectively (4.7% vs 9.4%, p< 0.001).

Conclusion/Discussion: In this national analysis of veterans with HIV, we found that only 15% received an anal pathology evaluation. The majority of initial anal evaluations were screening assessments with cytopathology (63%). We observed decreased anal evaluations from 2020 to 2023 but the proportion of screening assessments that were cytopathology remained stable. We identified screening differences by geographic region that corresponded to higher ASCC rates in the region with the least screening and lower ASCC rates in the region with the most screening.

Figure 1.
Initial anal pathologic evaluations (screening assessments with cytopathology vs diagnostic assessments with histopathology) in veterans with HIV from 2006-2023. (We were unable to calculate proportions of cytopathology and histopathology for 1999-2005 due to missing data in the VA Corporate Data Warehouse).