High Density of Intratumor CD45RO+ Memory Tumor-Infiltrating Lymphocytes Predicts Favorable Prognosis in Patients With Oral Squamous Cell Carcinoma

Abstract

Although tumor-infiltrating lymphocytes (TILs) have been increasingly appreciated as novel biomarkers for prognostic prediction in cancer, little attention has been paid to the CD45RO+ memory TIL and its associations with clinical outcomes in oral squamous cell carcinoma (OSCC). The purpose of this study was to determine the associations between CD45RO+ TILs and clinicopathologic parameters and prognosis in OSCC. Tissue sections of primary OSCC from 2 independent tertiary referral cancer centers (Nanjing and Wuxi, China) were retrospectively collected and subjected to immunohistochemical staining for CD45RO. Densities of CD45RO+ TILs in the tumor center (CT) and invasive margin were calculated. Optimal cutoff values of CD45RO+ TILs for patient stratification were generated by X-tile software. Kaplan-Meier and Cox regression analyses were performed to assess associations between CD45RO+ TILs and overall survival and recurrence-free survival. Prognostic prediction of CD45RO+ TILs was estimated by receiver operating characteristic (ROC) curve. One hundred sixty-nine eligible patients with OSCC were included. No relevant associations between CD45RO+ TILs and clinicopathologic parameters were identified. Kaplan-Meier analyses indicated that a high density of CD45RO TILs in the CT was significantly associated with favorable overall and recurrence-free survival (P=.0018 and .0007 by log-rank test). Cox proportional regression analyses showed that presence of CD45RO TILs in the CT was an independent prognostic factor for overall survival of OSCC. ROC curves showed that presence of CD45RO TILs in the CT was comparable to clinical stage in predicting patient survival, whereas their combination was superior to either parameter alone. The present findings indicate that intratumor density of CD45RO TILs is a viable and independent prognostic predictor for OSCC.