Prognostic Nutritional Index, Tumor-infiltrating Lymphocytes, and Prognosis in Patients with Esophageal Cancer

Objective: To determine whether prognostic nutritional index (PNI) affects clinical outcome through local immunity in esophageal cancers. Background: PNI is an indicator of nutritional status and systemic immune competence, and has attracted attention as a prognostic biomarker. Tumor-infiltrating lymphocytes (TILs) are a specific histological feature of human cancers, reflecting an individual's immunological tumor response. Methods: Using a nonbiased database of 337 curatively resected esophageal cancers, we evaluated the relationship between PNI, TILs status, CD8 expression by immunohistochemical staining, and clinical outcome. Results: Compared with PNI-high cases (n = 220), PNI-low cases (n = 117) showed significantly worse overall survival (log-rank P < 0.001; hazard ratio: 2.23; 95% confidence interval: 1.56–3.18; P < 0.001; multivariate hazard ratio: 1.67; 95% confidence interval: 1.14–2.44; P = 0.008). The TILs status was also significantly correlated with overall survival ( P < 0.001). In addition, PNI was significantly associated with TILs status ( P < 0.001) and the CD8-positive cell count ( P = 0.041). A significant relationship between the peripheral blood lymphocyte count and TILs status was also observed ( P < 0.001). Conclusions: PNI and TILs score expression were associated with clinical outcome in esophageal cancer, supporting their roles as prognostic biomarkers. Considering the relationship between PNI and TILs, nutritional status and systemic immune competence may influence patient prognosis through local immune response.