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Review
. 2021;65(6):501-509.
doi: 10.1159/000517078. Epub 2021 Jul 7.

PD-L1 Testing in Cytological Non-Small Cell Lung Cancer Specimens: A Comparison with Biopsies and Review of the Literature

Mohammed S I Mansour  1   2 , Kajsa Ericson Lindquist  3 , Tomas Seidal  1 , Ulrich Mager  4 , Rikard Mohlin  3 , Lena Tran  5 , Kim Hejny  1 , Benjamin Holmgren  1 , Despoina Violidaki  3 , Katalin Dobra  6 , Annika Dejmek  7 , Maria Planck  5   8 , Hans Brunnström  2   3
Affiliations
Review

PD-L1 Testing in Cytological Non-Small Cell Lung Cancer Specimens: A Comparison with Biopsies and Review of the Literature

Mohammed S I Mansour et al. Acta Cytol. 2021.

Abstract

Introduction: Programmed death-ligand 1 (PD-L1) expression is used for treatment prediction in non-small cell lung cancer (NSCLC). While cytology may be the only available material in the routine clinical setting, testing in clinical trials has mainly been based on biopsies.

Methods: We included 2 retrospective cohorts of paired, concurrently sampled, cytological specimens and biopsies. Also, the literature on PD-L1 in paired cytological/histological samples was reviewed. Focus was on the cutoff levels ≥1 and ≥50% positive tumor cells.

Results: Using a 3-tier scale, PD-L1 was concordant in 40/47 (85%) and 66/97 (68%) of the paired NSCLC cases in the 2 cohorts, with kappa 0.77 and 0.49, respectively. In the former cohort, all discordant cases had lower score in cytology. In both cohorts, concordance was lower in samples from different sites (e.g., biopsy from primary tumor and cytology from pleural effusion). Based on 25 published studies including about 1,700 paired cytology/histology cases, the median (range) concordance was 81-85% (62-100%) at cutoff 1% for a positive PD-L1 staining and 89% (67-100%) at cutoff 50%.

Conclusions: The overall concordance of PD-L1 between cytology and biopsies is rather good but with significant variation between laboratories, which calls for local quality assurance.

Keywords: 22C3; 28-8; Cell block; CytoLyt; Cytology; Histology; PreservCyt.

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Conflict of interest statement

The authors have no conflicts of interest to disclose.

Figures

Fig. 1
Fig. 1
An adenocarcinoma with concordant PD-L1 expression (both ≥50%) between paired EBUS cytology (a, b) and bronchial biopsy (c, d). Hematoxylin-eosin (a, c) and PD-L1 clone 22C3 (b, d). Scale bar, 20 μm. PD-L1, programmed death-ligand 1; EBUS, endobronchial ultrasound.
Fig. 2
Fig. 2
A squamous cell carcinoma with discordant PD-L1 expression (<1% vs. ≥50%) between paired EBUS cytology (a, b) and bronchial biopsy (c, d). Hematoxylin-eosin (a, c) and PD-L1 clone 22C3 (b, d). Scale bar, 20 μm. PD-L1, programmed death-ligand 1; EBUS, endobronchial ultrasound.
See this image and copyright information in PMC

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