CD8+ tumor-infiltrating lymphocytes as a novel prognostic biomarker in lung sarcomatoid carcinoma, a rare subtype of lung cancer

PURPOSE: The aim of this study was to investigate the degree of infiltration of CD8+ tumor-infiltrating lymphocytes (TILs) including high and low density in lung sarcomatoid carcinoma (LSC) and their clinicopathological significance. PATIENTS AND METHODS: The density of CD8+ TILs in paraffin-embedded tissue sections from 100 LSC patients was detected by immunohistochemical staining, and the relationship of CD8+ TILs with clinicopathological features and prognosis was analyzed. RESULTS: The chi-squared test showed that the degree of infiltration of CD8+ TILs was significantly correlated with the clinicopathological stage and T stage of LSC (P<0.05). The univariate analysis demonstrated that tumor size, clinicopathological stage, T stage, N stage, M stage, and CD8+ TILs are risk factors that affect prognosis of the patients (P<0.05). The mean overall survival (OS) of LSC patients with a high density of CD8+ TILs was 92.3 months, which was significantly higher than 31.2 months in patients with a low density of CD8+ TILs (P<0.05). Cox regression multivariate analysis confirmed that the density of CD8+ TILs was an independent prognostic factor for OS time of LSC patients (hazard ratio=0.455, P<0.05). CONCLUSION: CD8+ TILs could be used as an effective prognostic index for LSC patients, and a high density of CD8+ TILs in tumor tissue may predict a better outcome.