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.