Evaluation of the Implementation and Diagnostic Accuracy of the Paris Classification for Reporting Urinary Cytology in Voided Urine Specimens: A Cyto-Histological Correlation Study in a Cancer Center

Abstract

<b><i>Introduction:</i></b> The Paris classification highlights the need to focus on accurately identifying high-grade urothelial carcinoma (HGUC). Herein, we aimed to assess the overall implementation and diagnostic performance of the Paris classification for reporting urinary cytology in a cancer center. <b><i>Methods:</i></b> All urinary cytology reports from July 2018 to December 2019 were collected (<i>n</i> = 1,240). Only voided urine samples were included (<i>n</i> = 1,180). Risk of high-grade malignancy (ROHM) was calculated for each Paris category. The diagnostic performance of urinary cytology was assessed, including sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy. <b><i>Results:</i></b> The distribution of categories was: 0.3% unsatisfactory, 90.5% negative for HGUC, 5.6% atypical urothelial cells (AUC), 1.6% suspicious for HGUC, 1.9% HGUC, and 0.1% other malignancies. No diagnosis of low-grade urothelial neoplasia was given. The ROHM was 21.4% for negative for HGUC, 66.7% for AUC, 91.7% for suspicious for HGUC, and 100% for HGUC. When using suspicious for HGUC as a cutoff, the diagnostic performance of urinary cytology in identifying HGUC histology was 46% sensitivity, 98% specificity, 96% PPV, 68% NPV, and 74% accuracy. <b><i>Conclusion:</i></b> Specificity of urinary cytology was very high (with only 1 false-positive result), which is important since this will trigger a clinical intervention. The ROHM for each category was in accordance with literature, except for AUC where ROHM was slightly higher (66.7%). This may be explained by the study population characteristics (cancer center; many patients treated with intravesical therapies; lack of clinical annotation for patients referred from outside institutions).