BDNF and cancer: Unbalanced expression of neurotrophins Nerve Growth Factor (NGF), Brain-Derived Neurotrophic Factor (BDNF), Neurotrophin3 (NT3), and/or their receptors Tropomyosin related kinase A (TrkA), Tropomyosin receptor kinase B (TrkB), Tropomyosin receptor kinase C (TrkC), and common Neurotrophin Receptor p75 (p75NTR) have been reported in cancer [36,37].