LEP and neoplasm: There is evidence that many cytokines produced by tumor and immune cells can interact with neuropeptides and mediate cancer anorexia, which may explain the association between gastric cancer and AN.[42] For example, cytokines can mimic leptin signaling and suppress orexigenic ghrelin and neuropeptide Y (NPY) signaling to affect energy homeostasis and induce anorexigenic effect in cancer.[43,44]