Tumor Infiltrating Lymphocytes as an Independent Prognostic Factor in Undifferentiated Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma (NPC) is a common type of cancer in Southeast Asia. This cancer usually spreads locally and to nearby lymph nodes. One unique feature of NPC is its many immune cells called tumor-infiltrating lymphocytes (TILs). Recent studies have suggested that TILs in many types of cancer can indicate a better prognosis. However, the role of TILs in NPC is still a matter of debate. Further research is necessary to determine whether TILs can be used as a prognostic factor of NPC's outcome.

A retrospective cohort study was conducted at Sardjito Hospital to examine the records and pathological sections of patients treated for the undifferentiated subtype of NPC. Two pathologists analyzed the presence of TILs using HE-stained slides. TILs were evaluated in stromal compartments, and their association with clinicopathological variables was analyzed using the Chi-square and Fisher exact tests. The study compared overall survival in tumor patients with varying TIL levels using Kaplan-Meier survival curves and the log-rank test. A Cox regression model was used for univariate and multivariate analyses to test the significance of different factors.

Out of the total 61 subjects, 16 (26.2%) had high stromal TILs (≥ 70%), and 45 (73.8%) had low stromal TILs (<70%). The subjects' sex, age, and tumor stage did not affect the OS. However, high stromal TILs (≥ 70%) showed a significant association with a longer OS (log-rank test p = 0.006, HR 0.37, 95% CI 0.17-0.79, log-rank p = 0.006). Moreover, multivariate analysis confirmed that TILs were an independent prognostic indicator for OS (aHR 0.015).

TILs correlate positively with overall survival in the undifferentiated NPC subtype and are an independent prognostic indicator.