InterobServer AgreeMent in Pd‐l1 evaLuatIoN on cytoloGical samples—SAMPLING project: A multi‐institutional, international study

• DOI: 10.1002/cncy.70003
• Publication Date: 2025-02-26T16:46:24Z
• Authors: Gennaro Acanfora; Antonino Iaccarino; Bruna Cerbelli; Claudio Di Cristo...; Claudio Bellevicine; Massimo Barberis; Emanuela Bonoldi; Lukas Bubendorf; Andreas Calaminus; Severo Campione; Sule Canberk; Alberto Cavazza; Giorgio Cazzaniga; Obinna Chijioke; Eduardo Clery; Albino Eccher; Marianne Engels; Vincenzo Fiorentino; Paolo Graziano; Izidor Kern; Ivana Kholova; Jari Laatta; Tania Labiano; Martina Leopizzi; Maria D. Lozano; Rita Luis; Elisabetta Maffei; Alessandro Marando; Maurizio Martini; Elisabetta Merenda; Marco Montella; Allan Argueta Mor...; Michiya Nishino; Fabio Pagni; Paul Hofman; Angelina Pernazza; Sinchita Roy‐Chow...; Mauro Saieg; Spasenija Savic P...; Momin T. Siddiqui; Tajana Stoos‐Veic; Margareta Strojan...; Dinka Sundov; Paul VanderLaan; Danijela Vrdoljak...; Pio Zeppa; Giancarlo Troncone; Elena Vigliar

AbstractIntroductionThe aim of this project is to assess interobserver agreement for programmed death‐ligand 1 (PD‐L1) scoring on of non–small cell lung cancer (NSCLC) on cytological specimens in a large‐scale multicenter study, by exploiting the cell block‐derived tissue microarray (cbTMA) approach.MethodsA total of 65 cell blocks (CB) diagnosed as NSCLC were retrospectively collected and selected for TMA preparation. Hematoxylin–eosin and PD‐L1 stained slides were digitized and uploaded on a free web sharing platform. Participants were asked to provide PD‐L1 assessment by using the clinically relevant cutoff of tumor proportion score (TPS) (<1%; 1%–49%; >50%). Interobserver agreement was calculated using Fleiss’s κ.ResultsOf 65 CBs, 11 were deemed not suitable; therefore, an overall number of 54 cores were used for the preparation of four TMAs. A total of 1674 evaluations were provided by 31 cytopathologists from 21 different institutions in nine countries. The statistical analysis showed a moderate overall agreement (κ = 0.49). The highest agreement was achieved in the TPS >50% category (κ = 0.57); moderate agreement was observed in TPS <1% category (κ = 0.51) and the lowest κ value was obtained for TPS 1%–49% category (k = 0.32).ConclusionsThe overall moderate agreement observed showed that there is still room for improvement in inter‐pathologist agreement for PD‐L1 evaluation on cytological samples, highlighting the need for standardization in sample preparation, focused training in PD‐L1 evaluation on cytological material, and the integration of machine learning tools to improve interobserver consistency.