Prognostic Value of Tumor Proportion Score in Salivary Gland Carcinoma.

OBJECTIVE: Limited information is available regarding the role of programmed death ligand 1 (PD-L1) expression and CD8+ tumor-infiltrating lymphocyte (TIL) density in the tumor immune microenvironment (TIM) of patients with salivary gland carcinoma (SGC). This study aimed to assess the association between the prognosis of SGC patients and the probability of PD-L1 expression in tumor and/or immune cells using the tumor proportion score (TPS), mononuclear immune cell density score (MIDS), combined positive score (CPS), and CD8+ TIL density in the TIM. STUDY DESIGN: Retrospective cohort study. METHODS: We retrospectively reviewed 73 SGC patients treated with definitive surgery between 2000 and 2015. Immunohistochemical analysis was used to assess TPS, MIDS, CPS, and CD8+ TIL density, followed by prognostic evaluation of these immune-related parameters. RESULTS: Histological grade was associated with TPS, MIDS, and CPS based on PD-L1 expression, and these scores exhibited a significant association with CD8+ TIL density. Patients with positive TPS had an unfavorable disease-free survival and overall survival. Multivariate analyses indicated that the TPS was a significant and independent prognostic factor. CONCLUSION: Our results suggest that TPS might be a useful prognostic biomarker in SGC patients receiving definitive surgery. Laryngoscope, 131:E1481-E1488, 2021.