Aims Pulmonary squamous cell carcinoma (SqCC) represents the second most common non-small cell lung carcinoma type. The mechanisms which regulate programmed death ligand 1 (PD-L1) expression in this form of lung cancer are not fully elucidated yet.
Methods We immunohistochemically determined the level of PD-L1 expression using the Tumour Proportion Score system in surgical resections of 133 patients with pulmonary SqCC. The results from PD-L1 immunohistochemistry were analysed in relation to tumour differentiation and the presence of necrotic areas comprising at least 20% of the tumour mass.
Results No significant differences in terms of PD-L1 expression were found between SqCC subtypes as defined by the current WHO classification: better differentiated, keratinising tumours (12/24, 50.0 %) compared with less differentiated, non-keratinising and basaloid forms (62/109, 56.9 %) were PD-L1 positive in a comparable proportion of cases (p=0.1903). Contrary to that, SqCCs with the presence of necrosis (51/61, 83.6 %) had significantly more PD-L1-positive cases (p<0.001) compared with SqCCs without necrotic areas (23/72, 32.0 %)
Conclusions We demonstrated that PD-L1 expression in pulmonary SqCCs does not correlate with the traditionally defined degree of differentiation of these tumours. On the other hand, we found a significant association between the positive result of PD-L1 immunohistochemistry and tumour necrosis. Further investigation regarding the role of hypoxic pathways as presumable inducers of PD-L1 expression in pulmonary SqCCs might contribute to the understanding of this phenomenon.
- lung neoplasms
Data availability statement
Data are available upon reasonable request. Deidentified patient data.
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Handling editor Runjan Chetty.
Contributors All authors contributed to the conception and design of the final version of this manuscript and approved it. VT and LP designed the study, analysed and interpreted the results, and drafted the manuscript. MG performed the statistical analysis. AL drafted the work. AF, ZH and ZK collected and analysed the study material. LP supervised the study.
Funding This publication was created thanks to support under the Operational Programme Integrated Infrastructure for the project: Integrative strategy in development of personalized medicine of selected malignant tumours and its impact on quality of life, IMTS: 313011V446, co-financed by the European Regional Development Fund.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.