Molecular parameters of head and neck cancer metastasis.

Metastasis remains a major cause of mortality in patients with head and neck squamous cell carcinoma (HNSCC). HNSCC patients with metastatic disease have extremely poor prognoses, with an average survival rate of less than a year. Metastasis is an intricate sequential process that requires a discrete population of tumor cells to possess the capacity to intravasate from the primary tumor into systemic circulation, survive in circulation, extravasate at a distant site, and proliferate in a foreign, hostile environment. Literature has accumulated to provide mechanistic insight into several signal transduction pathways, receptor tyrosine kinases (RTKs), signal transducer and activator of transcription 3 (Stat3), Rho GTPases, protein kinase Cε (PKCsε), and nuclear factor-κB (NF-κB), that are involved in mediating a metastatic tumor cell phenotype in HN-SCC. Herein we highlight accrued information regarding the key molecular parameters of HNSCC metastasis.