• Fumihiko Sato, Takeharu Ono, Akihiko Kawahara, Toshihiko Kawaguchi, Hisaichiro Tanaka, Kazuhide Shimamatsu, Tatsuyuki Kakuma, Jun Akiba, Hirohito Umeno, and Hirohisa Yano.
• Department of Otolaryngology-Head and Neck Surgery, Kurume University School of Medicine, Kurume, Japan.
• J. Clin. Pathol. 2019 Aug 1; 72 (8): 542-549.

AimsLimited information is available regarding the precise differences in the tumour immune microenvironment (TIM) of patients with human papilloma virus (HPV)-associated and non-HPV-associated oropharyngeal squamous cell carcinoma (OPSCC). Here, we retrospectively reviewed 137 patients with OPSCC treated with a definitive treatment to identify molecular relationships in the TIM.Materials And MethodsWe used immunohistochemical analysis to assess p16 status, programmed death ligand 1 (PD-L1) level, and/or CD8+ tumour-infiltrating lymphocyte (TIL) density, followed by prognostic evaluation of these immune-related parameters.ResultsMultivariate analyses demonstrated that PD-L1 level on immune cells but not on tumour cells or CD8+ TIL density was a significant predictive factor of disease-free survival (DFS) and overall survival (OS). Additionally, subgroup analyses demonstrated that patients positive for p16 and PD-L1 expression on immune cells had favourable DFS and OS, whereas patients negative for p16 and PD-L1 expression on immune cells showed worse DFS and OS.ConclusionsWe demonstrated that PD-L1 expression on immune cells but not tumour cells might represent a useful prognostic biomarker in patients with OPSCC receiving a definitive treatment. We propose that a co-assessment of p16 and PD-L1 expression on immune cells would have greater prognostic potential compared with evaluation of each factor alone in patients with OPSCC.© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.

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