The Prognostic Impact of Combined Tumor-Infiltrating Lymphocytes and Pretreatment Blood Lymphocyte Percentage in Locally Advanced Nasopharyngeal Carcinoma

PURPOSE: To explore the prognostic impact of combined tumor-infiltrating lymphocytes (TILs) and pretreatment peripheral lymphocyte percentage (LYM%) among patients with locally advanced nasopharyngeal carcinoma (LA-NPC). PATIENTS AND METHODS: TILs and pretreatment LYM% were retrospectively assessed in 253 LA-NPC patients who underwent chemoradiation therapy between January 2012 and December 2017. According to TILs and LYM% status, the patients were divided into three groups: high-risk group (HRG) (TILs–LYM% score = 0), middle-risk group (MRG) (TILs–LYM% score = 1), and low-risk group (LRG) (TILs–LYM% score = 2). The relationship between TILs level and LYM%, and also the associations of TILs–LYM% status with clinicopathological factors and survival, were evaluated. RESULTS: As a continuous variable, LYM% was significantly higher in TILs-high group. High TILs or high LYM% alone was significantly related to better 3-year disease-free survival (DFS), overall survival (OS), distant metastasis-free survival (DMFS) and locoregional relapse-free survival (LRRFS), respectively. Kaplan–Meier analysis and log-rank tests also revealed significant decreases in DFS, OS, DMFS, and LRRFS among LA-NPC patients with TILs–LYM% score of 0, 1, and 2 (all P <0.05). Further multivariate analyses showed that TILs–LYM% score was an independent factor affecting survival of the patients, and HRG (TILs–LYM% score = 0) had increased hazard ratios (HRs) for disease (HR = 6.89, P <0.001), death (HR = 8.08, P = 0.008), distant metastasis (HR = 7.66, P = 0.001), and local relapse (HR = 5.18, P = 0.013) compared with LRG (TILs–LYM% score = 2). In receiver operating characteristics (ROC) analyses, TILs–LYM% score had a higher area under the ROC curve (AUC) for the prediction of DFS than did TILs or LYM% alone. CONCLUSIONS: A positive correlation was found between TILs level and pretreatment blood lymphocyte percentage. Moreover, TILs–LYM% score can be considered as a novel independent prognostic indicator of survival outcome among patients with LA-NPC.