Interobserver reproducibility of a hybrid three-tier grading system of papillary nonmuscle invasive urothelial carcinoma: an international Uropathology study

Downes MR, Lajkosz K, Algaba F, Allory Y, Amin MB, Cheng L, Desai S, Eckstein M, Hartmann A, Lopez-Beltran A, Mannweiler S, van Montfoort ML, Oxley J, Paner GP, Samaratunga H, Shen S, Warrick J, Williamson SR, Wobker SE, van der Kwast TH (2025)

Publication Type: Journal article

Publication year: 2025

Journal

DOI: 10.1111/his.15438

Abstract

Aims: A hybrid-three tier system with low grade (LG), high grade- G2 (HG-G2), high grade- G3 (HG-G3) has been proposed in recognition of, and to help address, the clinical heterogeneity within high grade WHO 2004/2022. We assessed interobserver reproducibility amongst international uropathologists using this three-tier approach. Methods and Results: Papillary Ta nonmuscle invasive bladder cancer (NMIBC) specimens (n = 30) were selected and graded by two uropathologists and assessed using WHO 2004/2022 and WHO 1973 and categorized as LG (n = 15), HG-G2 (n = 8), HG-G3 (n = 7), and photographed at 10× and 20× magnification. Images were circulated via Survey Monkey to invited uropathologists who determined: (1) that image was LG or HG, and (2) if HG, assigned to G2 or G3. Model-based kappa measure of association was used to assess interrater agreement. Eighteen uropathologists:(eight North American, eight European, two other) assessed 60 images with 1076 gradings for analysis. The kappa value amongst Europeans versus North Americans was 0.663 versus 0.647 for 10× images and 0.682 versus 0.623 for 20× images. At 10×, agreement for LG, HG-G2, and HG-G3 was 74.6%, 63.6%, and 92.0%, and at 20× was 64.3%, 63.9%, and 95.2% respectively. Conclusion: Three-tier grading of papillary Ta NMIBC had substantial interobserver agreement amongst international uropathologists. The recognition of the HG-G3 case reached the highest concordance. North American uropathologists had comparable kappa scores (substantial agreement) to Europeans, despite being unaccustomed to separating HG cases into G2 and G3, demonstrating three-tier grading could be “quickly” adopted by genitourinary experts if endorsed and required by the relevant bodies in their jurisdiction of practice.

Authors with CRIS profile

Involved external institutions

Medizinische Universität Graz Austria (AT) Netherlands Cancer Institute - Antoni van Leeuwenhoek Hospital (NKI / NKI-AVL) Netherlands (NL) North Bristol NHS Trust United Kingdom (GB) University of Chicago United States (USA) (US) University of Queensland Australia (AU) Weill Cornell Medicine United States (USA) (US) Penn State College of Medicine United States (USA) (US) Cleveland Clinic United States (USA) (US) University of North Carolina at Chapel Hill United States (USA) (US) Princess Margaret Cancer Centre / Princess Margaret Hospital Canada (CA) Sunnybrook Health Sciences Centre Canada (CA) Fundació Puigvert Spain (ES) Institut Curie France (FR) The University of Tennessee Health Science Center United States (USA) (US) Brown University United States (USA) (US) University of Cordoba / Universidad de Córdoba (UCO) Spain (ES) Tata Memorial Hospital India (IN)

How to cite

APA:

Downes, M.R., Lajkosz, K., Algaba, F., Allory, Y., Amin, M.B., Cheng, L.,... van der Kwast, T.H. (2025). Interobserver reproducibility of a hybrid three-tier grading system of papillary nonmuscle invasive urothelial carcinoma: an international Uropathology study. Histopathology. https://doi.org/10.1111/his.15438

MLA:

Downes, Michelle R., et al. "Interobserver reproducibility of a hybrid three-tier grading system of papillary nonmuscle invasive urothelial carcinoma: an international Uropathology study." Histopathology (2025).

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