BDNF and head and neck squamous cell carcinoma: These data are consistent with the published evidence that the BDNF (which is sufficiently available in HNSCC)–TrkB (the receptor is available in 40% of the cases, frequently focally localized at the border of the tumor cell nests) system might be related with cell invasivity, and improved tumor cell survival in therapeutic conditions [13,16,18,19,22].