Correlation of PD-L1 expression with p16INK4A expression in nonoropharyngeal head and neck squamous cell carcinoma.

39Background: The expression of PD-L1 expression is important for tumor cells to evade the immune system. The level of its expression and its correlation to disease prognosis is unclear in non-oropharyngeal head and neck squamous cell carcinoma (non-OPHNSCC). Methods: A retrospective clinicopathologic analysis was performed for 106 non-OPHNSCC patients diagnosed during the period from 2007 to 2014. We made tissue arrays from the paraffin-embedded non-OPHNSCC samples obtained from the patients, and studied PD-L1 and p16INK4A expression by immunohistochemistry. Systemic inflammatory factors including C-reactive protein, serum white blood cell, neutrophil, monocyte, and lymphocyte count were also analyzed to study the correlation. Results: We found that PD-L1 was overexpressed in 32.1% (34/106) and p16INK4A in 20.8% (22/106) of the patients who were studied. The expression of PD-L1 was associated with p16INK4A expression (p < 0.01), but was not associated with the level of systemic inflammatory factors. No s...