IL13 and cancer: In this study, we have chosen interleukin-13 (IL-13) and transforming growth factor beta (TGF-β), i.e., two cytokines with presumed roles in the development of cancer cachexia, and we measured their concentrations in the serum and saliva of cachectic patients with metastatic solid tumors, non-cachectic patients with metastatic solid tumors, and healthy individuals.