FGF2 and head and neck squamous cell carcinoma: The soluble tumor factors are induced by tumor cells that produce several growth factors, such as the epidermal growth factor (EGF); fibroblastic growth factor (FGF); transformant growth factor-beta (TGF-β); cytokines, such as IL-4, IL-6, IL-8, and IL-10; GM-CSF; vascular endothelial growth factor (VEGF); prostaglandin E2 (PGE2); and basic fibroblast growth factor (bFGF), which are involved in the pathogenesis of HNSCC and provide several tumor properties (inhibition of apoptosis, inflammation regulation, angiogenesis, and metastasis) related to prognosis [133,134,135,136,137].