Cancer cachexia syndrome in head and neck cancer patients: Part II. Pathophysiology.

Cancer cachexia is a morbid wasting syndrome common among patients with head and neck cancer. While its clinical manifestations have been well characterized, its pathophysiology remains complex. A comprehensive literature search on cancer cachexia was performed using the National Library of Medicine's PubMed. The Cochrane Library and Google search engine were also used. Recent evidence and new concepts on the pathophysiology of cancer cachexia are summarized. Targeted therapies are presented, and new concepts are highlighted. Cancer cachexia is characterized by complex, multilevel pathogenesis. It involves up-regulated tissue catabolism and impaired anabolism, release of tumor-derived catabolic factors and inflammatory cytokines, and neuroendocrine dysfunction. These culminate to create an energy-inefficient state characterized by wasting, chronic inflammation, neuroendocrine dysfunction, and anorexia.