Prognostic Significance of Serine-Phosphorylated STAT3 Expression in pT1-T2 Oral Tongue Carcinoma

OBJECTIVES: Phosphorylated (activated) STAT3 (pSTAT3) is a regulator of numerous genes that play an essential part in the onset, development and progression of cancer; it is involved in cell proliferation and preventing apoptosis, and in invasion, angiogenesis, and the evasion of immune surveillance. This study aimed mainly to investigate the potential prognostic role of pSTAT3 expression in oral tongue squamous cell carcinoma (SCC). METHODS: Phospho-ser727 STAT3 immunolabeling was correlated with prognostic parameters in 34 consecutive cases of pT1-T2 tongue SCCs undergoing primary surgery. Computer-based image analysis was used for the immunohistochemical reactions analysis. RESULTS: Statistical analysis showed a difference in disease-free survival (DFS) when patients were stratified by pN status (P=0.031). Most tumors had variable degrees (mean±SD, 80.7%±23.8%) of intense nuclear immunoreaction to pSTAT3. Our findings rule out any significant association of serine-phosphorylated nuclear STAT3 expression with tumor stage, grade, lymph node metastasis, recurrence rate, or DFS. CONCLUSION: In spite of these results, it is worth further investigating the role of pSTAT3 (serine- and tyrosine-pSTAT3) in oral tongue SCC in larger series because preclinical models are increasingly showing that several anticancer strategies would benefit from STAT3 phosphorylation inhibition.