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

BACKGROUND: Screening for anal dysplasia and human papilloma virus 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. OBJECTIVE: This is a pilot study to determine if patient-sampled screening is feasible and accurate compared to physician-sampled anal dysplasia screening. DESIGN: Single-center prospective trial. SETTINGS: A single tertiary care center. PATIENTS: Fifty patients over 35 years old, who are HIV-positive, participated in anoreceptive intercourse, and without a previous diagnosis of anal cancer were recruited. INTERVENTION: 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 human papilloma virus and anal dysplasia testing. Patients also completed a questionnaire on their perceptions of the self-collection and willingness to pursue this in the future. MAIN OUTCOME MEASURES: Accuracy, sensitivity, and specificity of pathology results. RESULTS: For detecting the presence of atypical cells, patient-collected samples had 72.0% accuracy, 85.7% sensitivity, 72.0% specificity, 72.0% positive predictive value, and 85.7% negative predictive value. Cytology classification had moderate agreement between patient and physician-collected samples (Cohen's κ = 0.51, p < 0.01). For detecting the presence of high-risk human papilloma virus, patient-collected samples had 83.7% accuracy, 87.5% sensitivity, 81.8% specificity, 70.0% positive predictive value, and 93.1% negative predictive value. Human papilloma virus subtype classification had moderate agreement between patient and physician-collected samples (Cohen's κ = 0.63, p < 0.01). LIMITATIONS: This is a single-institution pilot study with a small sample size, limiting generalizability. CONCLUSIONS: Preliminary results show promising results for patient administered anal dysplasia sampling, and most patients have confidence in the results. At-home screening could be a feasible method for increasing anal dysplasia screening. See Video Abstract.