Considerable interlaboratory variation in PD-L1 positivity in a nationwide cohort of non-small cell lung cancer patients. (September 2021)

• Record Type: Journal Article
• Authors: Koomen, Bregje M.; Voorham, Quirinus J.M.; Epskamp-Kuijpers, Chantal C.H.J.; van Dooijeweert, Carmen; van Lindert, Anne S.R.; Deckers, Ivette A.G.; Willems, Stefan M.
• Is Part Of: Lung cancer. Volume 159(2021)
• Page Start: 117
• Page End: 126
• Publication Date: 2021-09
• Subjects: CCMO Central Committee on Research involving Human Subjects -- EMA European Medicines Agency -- EQA external quality assessment -- GDPR General Data Protection Regulation -- IHC immunohistochemistry -- LDT laboratory-developed test -- NSCLC non-small cell lung cancer -- PD-1 programmed death receptor-1 -- PD-L1 programmed death ligand-1 -- TCs tumor cells -- TPS tumor proportion score; Non-small cell lung cancer -- Programmed death-ligand 1 -- Immunohistochemistry -- Clinical pathology -- Interlaboratory variation; Lungs -- Cancer -- Periodicals; Lung Neoplasms -- Abstracts; Lung Neoplasms -- Periodicals; Poumons -- Cancer -- Périodiques; Lungs -- Cancer; Periodicals; Electronic journals; Electronic journals; 616.99424
• DOI: 10.1016/j.lungcan.2021.07.012
• Languages: English
• ISSNs: 0169-5002

Abstract

Highlights: Considerable variation in PD-L1 positivity exists between pathology laboratories. Variation is greatest when PD-L1 positivity is determined according to the 1% cutoff. This variation could negatively influence treatment decisions for NSCLC patients. Abstract: Objectives: Immunohistochemical expression of programmed death-ligand 1 (PD-L1) is used as a predictive biomarker for prescription of immunotherapy to non-small cell lung cancer (NSCLC) patients. Accurate assessment of PD-L1 expression is therefore crucial. In this study, the extent of interlaboratory variation in PD-L1 positivity in the Netherlands was assessed, using real-world clinical pathology data. Materials and Methods: Data on all NSCLC patients in the Netherlands with a mention of PD-L1 testing in their pathology report from July 2017 to December 2018 were extracted from PALGA, the nationwide network and registry of histo- and cytopathology in the Netherlands. PD-L1 positivity rates were determined for each laboratory that performed PD-L1 testing, with separate analyses for histological and cytological material. Two cutoffs (1% and 50%) were used to determine PD-L1 positivity. Differences between laboratories were assessed using funnel plots with 95% confidence limits around the overall mean. Results: 6, 354 patients from 30 laboratories were included in the analysis of histology data. At the 1% cutoff, maximum interlaboratory variation was 39.1% (32.7%−71.8%) and ten laboratories (33.3%) differed significantly from the mean. Using the 50% cutoff, four laboratories (13.3%) differed significantly from the mean and maximum variation was 23.1% (17.2%−40.3%). In the analysis of cytology data, 1, 868 patients from 23 laboratories were included. Eight laboratories (34.8%) differed significantly from the mean in the analyses of both cutoffs. Maximum variation was 41.2% (32.2%−73.4%) and 29.2% (14.7%−43.9%) using the 1% and 50% cutoffs, respectively. Conclusion: Considerable interlaboratory variation in PD-L1 positivity was observed. Variation was largest using the 1% cutoff. At the 50% cutoff, analysis of cytology data demonstrated a higher degree of variation than the analysis of histology data.