ABSTRACT
<p><b>OBJECTIVE</b>To investigate the infiltration and prognostic significance of tumor-infiltrating mast cells (TIMs) in nasopharyngeal carcinoma (NPC).</p><p><b>METHODS</b>Immunohistochemistry 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.</p><p><b>RESULTS</b>TIM 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.</p><p><b>CONCLUSIONS</b>The density of TIM in NPC increased with tumor stage. High TIM infiltration was associated with poor overall survival and progression-free survival.</p>