Anal PAP, HPV tests and magnifying chromoendoscopy with biopsies in the diagnosis of anal intraephitelial neoplasia

Abstract

Introduction Anal intraepithelial neoplasia (AIN) is the most likely precursor of squamous cells cancer which represents 90% of anal cancers. The use of biomolecular tests as a screening method has been extended by gynecology. Given the similarities that exist between the HPV disease in the lower genital tract and anorectal sectors, it is expected that HPV tests can provide information for the diagnosis, treatment and follow-up for AIN-affected patients. Objectives Comparing the performance of anal cytology, PAP and HPV tests (Hybrid Capture and Papillocheck) against the histology of the diagnosis of low- and high-grade AIN in risk groups. Material and methods A cross-sectional study was carried out to evaluate diagnostic methods for low- and high-grade AIN in 73 patients. Samples for anal PAP, Papillocheck and Hybrid Capture were taken from all patients who then, regardless of the results, underwent magnifying chromoendoscopy (MCE) along with biopsy. Diagnostic test performances and their 95% confidence intervals (CI: 95%) were calculated as well as the likelihood ratio for each test. Results Of the 73 patients, 49 (67%) were women. The average age of the patients was 38 years. In 38 patients (52%), the histology was positive with 10 (14%) grade II AIN or higher. There were no statistically significant differences in sensitivity nor in specificity for low- and high-grade AINs between any of the tests. Conclusion Anal PAP, the Hybrid Capture test (HC2, Qiagen) and PapilloCheck (Greiner Bio One) were highly sensitive but not specific for low- and high-grade AINs. Therefore, a biopsy should be conducted against a positive result of any of the tests to confirm AIN and the degree of dysplasia. The screening method selection depend on the availability but also costs of the test should be considered, since all the diagnostic tests have similar performance.