Prognostic markers in oropharyngeal squamous cell carcinoma: focus on CD70 and tumour infiltrating lymphocytes

We evaluated the expression of CD70 as biomarker for prognosis in patients with oropharyngeal squamous cell carcinoma (OSCC). We also examined the prognostic value of tumour infiltrating lymphocytes (TILs) in our study cohort. Formalin fixed, paraffin embedded tissue originating from the oropharynx of 78 patients was immunohistochemically stained for CD70, CD3, CD8 and FoxP3. Expression of CD70, CD3, CD8, FoxP3 and HPV status was correlated with clinicopathological characteristics. Overall survival (OS) was determined by a log-rank (Mantel-Cox) test whereas the Cox proportional hazard model was used for multivariate analysis. CD70 expression demonstrated no influence on OS. Tumours heavily infiltrated by TILs were linked with better outcome, for the total number of TILs as well as for the CD3(+) and CD8(+) T cell count. A Cox proportional hazard model proved that solely CD8(+) infiltrating T cells exhibit a positive effect on OS (HR = 0.30, 95% confidence interval 0.13-0.72). Our results demonstrate that CD8(+) TILs constitute an independent prognosticator in patients diagnosed with OSCC. Further validation of the prognostic value of CD8(+) TILs in OSCC is warranted and could provide us with a better insight into the immunological status of these malignancies.