Prognostic significance of tumor-infiltrating lymphocytes in nondisseminated nasopharyngeal carcinoma: A large-scale cohort study

The American Joint Committee on Cancer (AJCC) staging system is inadequate for an accurate prognosis in nasopharyngeal carcinoma (NPC). Thus, new biomarkers are under intense investigation. Here, we investigated whether the density of TILs could predict prognosis in NPC. First, we used 1490 cases of nasopharyngeal carcinoma samples from two independent cohorts to evaluate the density and distribution of tumor-infiltrating lymphocytes (TILs). Second, in one cohort, we assessed associations between TILs and clinical outcomes in 593 randomly selected samples (defined as the training set) and validated findings in the remaining 593 samples (defined as the validation set). Furthermore, we confirmed the prognostic value of TILs in a second independent cohort of 304 cases (defined as the independent set). Based on multivariable Cox regression analysis, we also established an effective prognostic nomogram including TILs to improve accuracy in predicting disease-free survival (DFS) for patients with nondisseminated NPC. We found that high TILs in the training set were significantly associated with favorable DFS [hazard ratio (HR) 0.41, 95% confidence interval (CI) 0.28-0.58, p < 0.001], overall survival (OS, HR 0.42, 95% CI 0.27-0.64, p < 0.001), distant metastasis-free survival (DMFS, HR 0.37, 95% CI 0.23-0.58, p < 0.001) and local-regional recurrent free survival (LRRFS, HR 0.43, 95% CI 0.25-0.73, p = 0.002). Multivariate analysis showed that TILs are an independent prognostic indicator for DFS in all cohorts. In summary, this study indicated that TILs may reflect the immunological heterogeneity of NPC and could represent a new prognostic biomarker.