Prognostic Role of Tumor-Infiltrating Lymphocytes in Esophagus Cancer: a Meta-Analysis

Abstract

Background/Aims: Several studies have verified the correlation between tumor-infiltrating lymphocytes (TILs) and survival of patients with esophagus cancer (EC). However, the prognostic role of TILs is still controversial. Therefore, we performed this meta-analysis. Methods: We searched PubMed, Embase and the Cochrane Library (last update by August 30, 2017) to identify studies assessing the effect of TILs on survival of patients with EC. Pooled hazard ratios (HRs) for overall survival (OS), disease-free survival (DFS) and cancer specific survival (CSS) were estimated using fixed-effects models or random-effects models, which depends on the heterogeneity. Results: Data from 22 observational studies including 2909 patients were summarized. Pooled analysis indicated that generalized TILs were favorable prognostic markers for OS in patients with EC (pooled HR = 0.48; 95% CI = 0.38-0.61; P < 0.001). For TIL subsets, CD8+ TILs were associated with improved OS (pooled HR = 0.68; 95% CI = 0.58–0.84; P < 0.001) and DFS (pooled HR = 0.90; 95% CI = 0.85-0.95; P < 0.001); FoxP3+ TILs were associated with patients’ DFS (pooled HR = 0.88; 95% CI = 0.81-0.96; P = 0.003). High CD57+ TILs indicated a better OS in patients with EC (pooled HR = 0.50; 95% CI = 0.35-0.72; P < 0.001). In addition, the pooled results showed that other TIL subsets including CD3+, CD4+ and CD45RO+ TILs were not associated with patients’ survival (P > 0.05). Conclusions: For patients with EC, some TIL subsets could serve as prognostic biomarkers. The application of TILs in the immunotherapy of EC needs to be verified through a large amount of clinical research.