GDF15 and cancer: Cachexia is a multifactorial syndrome frequently associated with cancer that includes loss of skeletal muscle, fatigue, functional impairment, decreased quality of life (QoL), and decreased survival, characterized by anorexia and unintended weight loss [8] and increased serum or tumor microenvironment concentrations of certain cytokines, such as tumor necrosis factor-α, interleukin (IL)-6, IL-8, and growth differentiation factor-15.