LEP and Anorexia: The relationships between cancer and pro-inflammatory cytokines often lead to nutritional deterioration and poor quality of life; cytokines influence the balance of anorexigenic circuits and orexigenic, that predispose to cancer anorexia–cachexia, which involve the interplay of mediators, including hormones like neuropeptides, leptin, cytokines (e.g., interferon, interleukin 6 (IL-6), tumor necrosis factor alpha [TNF-α], interleukin 1 (IL-1)), and differentiation factor [13].