P102 - The THOMAS Study: A Pilot Study for Patient-Administered Anal Cancer Screening

Purpose/Background: Screening for anal dysplasia and HPV allows for appropriate surveillance and treatment, but not all patients are willing or able to have this test performed in a physician's office. At-home testing may be a viable option to expand access to anal dysplasia screening, but its feasibility and reliability have not yet been tested. This is a pilot study to determine if patient-sampled screening is safe and effective.

Methods/Interventions: This is a single-center prospective trial. Patients over 35 years old who are HIV-positive, participated in anoreceptive intercourse, and without a previous diagnosis of anal cancer were recruited. Eligible participants were provided written instructions and self-collected a sample independently, followed by another anal swab performed by a physician. Both samples were submitted to pathology for HPV and anal dysplasia testing. Cohen's κ coefficient was calculated to determine agreement between physician-collected and patient-collected samples in addition to sensitivity and specificity. Participants also completed a questionnaire on their perceptions of the self-collection and willingness to pursue this in the future. Participant follow up was directed by their physician-collected swab results.

Results/Outcomes: This study is ongoing and all results are preliminary. Within the first 7 months, 34 patients were enrolled. Pathology and HPV testing data was available for 30 patients. The T zone was obtained in 50% of clinician-collected samples and 38% of patient-collected samples. Using physician-collected samples as the standard, detection of dysplasia (NILM vs non-NILM) was 73.3% accurate for patient-collected samples with 60% sensitivity, 86.7% specificity, and significant agreement (Cohen's κ = 0.47, p< 0.01). For specific dysplasia staging, clinician and patient-acquired samples were identical in 20 patients. The clinician sample was better than the patient sample in 5 patients and the patient sample was better than the clinician sample in 9 patients. HPV testing was 80% accurate with 58.3% sensitivity, 94.4% specificity, and significant agreement (Cohen's κ = 0.56, p< 0.01). With regards to subjective perceptions on self-administered testing, 100% of patients endorsed that they would "somewhat" or "completely" trust the results of a self-administered screening, though 28.9% answered that they would prefer the test be done by a healthcare provider. In a post-collection survey, 82.4% felt "somewhat comfortable" or "very comfortable" performing the test themselves.

Conclusion/Discussion: Preliminary results show promising results for patient administered anal dysplasia sampling, and the majority of patients have confidence in the results. At-home screening could be a valid method for increasing HPV and anal cancer screening.

Accuracy of patient-collected anal swab compared to physician-collected anal swab
Abbreviations: HPV: human papillomavirus; NILM: negative for intraepithelial lesion or malignancy; ASC-US: atypical squamous cells of undetermined significance; ASC-H: atypical squamous cells, cannot rule out high grade; LSIL: low-grade squamous intraepithelial lesion; HSIL: high-grade squamous intraepithelial lesion