Sato F, et al. - The researchers retrospectively reviewed 137 subjects with oropharyngeal squamous cell carcinoma (OPSCC) treated with a definitive treatment in order to recognize molecular links in the tumor immune microenvironment. Immunohistochemical analysis to evaluate p16 status programmed death-ligand 1 (PD-L1) level, and/or CD8⁺ tumor-infiltrating lymphocyte (TIL) density, followed by the prognostic assessment of these immune-related parameters was done. PD-L1 level on immune cells an important predictive factor of disease-free survival (DFS) and overall survival (OS) but not on tumor cells or CD8⁺ TIL density. Subjets positive for p16 and PD-L1 expression on immune cells had favorable DFS and OS, whereas subjects negative for p16 and PD-L1 expression on immune cells exhibited worse DFS and OS. Hence, in subjects with OPSCC receiving definitive treatment, PD-L1 expression on immune cells but not tumor cells might factor as a beneficial prognostic biomarker. In comparison with the assessment of each factor alone in subjects with OPSCC, a co-evaluation of p16 and PD-L1 expression on immune cells would have greater prognostic potential.