Use of T-cell infiltrate to predict long-term survival following local therapy in tongue cancer patients.

Abstract

5547 Background: Oral tongue squamous cell cancer (OTSCC) is one of the most aggressive subtypes in head and cancers. Currently, the most reliable prognostic indicator for OTSCC patients is the status of cervical lymph nodes. Identification of differences in tumor microenvironment might be of prognostic value in this type of cancer. Of those, the clinicopathologic significance of the tumor-infiltrating lymphocytes (TIL) in various human cancers has been an issue of great interest. However, importance of TIL in OTSCC has rarely been reported. The purpose of this study was to investigate whether the degree of TIL in the surgical specimens of OTSCC can be used to predict the clinical outcome following resection. Methods: We performed an immunohistochemical study to identify and count the number of CD4+ T cells, Foxp3+ regulatory T cells, Ki-67+ cells, and CD105+ cells in cancer nests and stroma in surgical specimens obtained from 53 OTSCC patients. Microvessel density (MVD) was measured with a light microscope in a single area of invasive tumor (200x field or 0.74 mm2) representative of the highest microvessel density. Correlation between the degree of TIL and clinicopathological variables, and survival rate were analyzed. Results: Patients with high TIL in cancer nests had significantly longer survival time than those with low TILs (5-year survival rate; 70% vs 33.9%, p=0.039). High density of TIL was observed more frequently in the patients who were current smokers or alcohol drinkers. Subsequent multivariate analysis revealed that degree of TIL was an independent prognostic factor in the patients with smoking associated cancers only (p=0.023 in Cox proportional hazard model), but not in non-smokers. In addition, higher MVD was observed in patients with high TIL. However, ratio of foxp3+ regulatory T cell did not correlate with survival in our patient series. Conclusions: Our data show that total T cell infiltrate in the invasive tumor is significantly correlated with overall survival time in patients with OTSCC after resection. Significant impact on survival of TIL was found only in patients with smoking-related cancer, suggesting immune response may play an important role in prognosis of smoking-related OTSCC. No significant financial relationships to disclose.