TPS 2.0-based voided urine cytology from patients with pathologically-proven low-grade urothelial carcinoma: Comparison with TPS 1.0 and JRSUC 2015.

BACKGROUND The Paris System (TPS) 1.0 for reporting urinary cytology focused on high-grade urothelial carcinoma (HGUC) but included low-grade urothelial neoplasm (LGUN) category by evaluating cell clusters. The 2015 Japan Reporting System for Urinary Cytology (JRSUC 2015) also includes low-grade urothelial carcinoma (LGUC) category. Then, TPS 2.0 deleted the LGUN category and completely focused on HGUC detection by evaluating only individual cells. We aimed to investigate this impact from the perspective of pathologically-proven LGUC diagnosis. METHODS Voided urine samples, suspected of new-onset bladder cancer, with corresponding pathological diagnosis within three months of cytological diagnosis were analyzed. TPS 2.0-based cytology was statistically compared with TPS 1.0- and JRSUC 2015-based ones. RESULTS 189 cases, consisting of 27 pathologically-proven benign lesions, 63 LGUC, 96 HGUC, and 3 other malignancies were analyzed. Cytological diagnosis demonstrated high correlation between TPS 2.0 and JRSUC 2015 (r = 0.96, p < 0.001) and complete coincidence between TPS 2.0 and TPS 1.0 (r = 1.00, p < 0.001). One and none of 63 pathological LGUC was classified as cytological LGUC/LGUN by JRSUC 2015 and TPS 1.0, respectively, validating restricted utility of the LGUC/LGUN category. Cytological diagnosis of pathological LGUC was almost identical among three reporting systems. These systems demonstrated similar concordance levels with pathological diagnosis (TPS 1.0 and 2.0: both r = 0.483, p < 0.001; JRSUC 2015: r = 0.484, p < 0.001). CONCLUSION Even from the perspective of LGUC, TPS 2.0 would not be disadvantageous and is an excellent reporting system because of objectivity and simplicity.