OBJECTIVETo investigate the infiltration and prognostic significance of tumor-infiltrating mast cells (TIMs) in nasopharyngeal carcinoma (NPC).

METHODSImmunohistochemistry for tryptase was performed on 154 NPC specimens. The median value of TIM density was used as a cutoff point to separate the patient cohort into two groups with either low or high TIM infiltration. The associations between TIM and clinicopathological factors were analyzed by Mann-Whitney U text. Survival curves were plotted according to the Kaplan-Meier method. Univariate and multivariate analyses were performed using the Log-rank test and the Cox proportional hazard models, respectively. P<0.05 was considered statistically significant. All statistical analyses were conducted using SPSS 13.0.

RESULTSTIM was mainly in the stroma of NPC and detected in all specimens. The median value of TIM density (25.60/high power field) was used as a cutoff point to separate the patient cohort into two groups with either low or high TIM infiltration. The density of TIM was positively correlated with N stage (Z=-2.193, P<0.05) and clinical stage (Z=-2.551, P<0.05). The 3-year overall survival (OS) and progression-free survival (PFS) of patients were 64.4% and 55.7% in the high TIM density group; 78.3% and 77.0% in the low TIM density group. For survival evaluation, high density of TIM was associated with worse OS and PFS (P<0.05). Multivariate Cox regression model analysis showed TIM infiltration was an independent risk factor for both OS and PFS.

CONCLUSIONSThe density of TIM in NPC increased with tumor stage. High TIM infiltration was associated with poor overall survival and progression-free survival.