1. Department of Pathology, Saitama Medical University International Medical Center, Saitama, Japan
2. Oral Pathology and Medicine, Graduate School of Medicine Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan
3. Department of Head and Neck Oncology/Ear, Nose and Throat, Saitama Medical University International Medical Center, Saitama, Japan
Aims: Immunohistochemistry of PD-L1 has been recently established as a surrogate method to predict if immunotherapy targeting PD-L1/PD-1 has a significant effect on suppression of cancers such as lung non-small cell carcinoma, melanoma, and renal cell carcinoma. Here we performed immunohistochemistry for PD-L1 expression in squamous cell carcinoma (SCC) of the tongue to investigate the potential correlation between PD-L1 expression and clinicopathological factors and whether PD-L1 expression would be associated with prognosis.
Methods: Tissue microarray cores of paraffin-embedded blocks from 135 cases with surgically resected tongue SCC were immunohistochemically analysed for PD-L1 expression.
Results: We observed a positive correlation between PD-L1 expression and tongue SCC pT1 and pT2 tumours, but a negative correlation with pT2, pT3 and pT4 tumours. We also observed a positive correlation with lymph node metastasis. However, no positive correlation was demonstrated between PD-L1 expression and overall survival.
Conclusions: PD-L1 tends to be overexpressed at the early stage of tongue SCC, showing a close correlation with initial development of tongue. However, PD-L1 expression may not affect prognosis.
Keywords: PD-L1, immunohistochemistry, oral pathology, squamous cell carcinoma