Anal cytology in women with cervical intraepithelial or invasive cancer: interobserver agreement Citologia anal em mulheres com neoplasia intraepitelial ou invasiva cervical: concordância interobservadores

Introduction: Incidence rates of anal cancer have been rising worldwide in the last 20 years. Due to embryological, histological and immunohistochemical similarities between the anal canal and the cervix, routine screening with anal cytology for precursor lesions in high-risk groups has been adopted. Objective: To determine interobserver agreement for the diagnosis of anal neoplasia by anal cytology. Material and methods: A cross-sectional observational study was conducted in 324 women with cervical intraepithelial or invasive cancers, for screening of anal cancer, from December 2008 to June 2009. Three hundred twenty-four cytological samples were analyzed by three cytopathologists. Cytological evaluation was based on the revised Bethesda terminology; samples were also classified into negative and positive for atypical cells. We calculated the kappa statistic with 95% confidence interval (95% CI) to assess agreement among the three cytopathologists. Results: Interobserver agreement in the five categories of the Bethesda terminology was moderate (kappa for multiple raters: 0.6). Agreement among cytopathologists 1, 2 and 3 with a consensus diagnosis was strong (kappa: 0.71, 0.85 and 0.82, respectively). Conclusion: Interobserver agreement in anal cytology was moderate to strong, indicating that cervical cytomorphological criteria are reproducible also in anal samples.