Cancer cachexia and fatigue.

Cachexia is a disease process that develops in numerous chronic, end-stage disease processes (eg cancer, heart failure, AIDS, renal failure). It has no agreed definition but represents the complex metabolic process that occurs in patients with these conditions.1 Cachectic patients lose lean muscle mass as well as fat, unlike starvation where only fat stores are initially depleted. In addition, the muscle wasting of cachexia cannot be reversed by increased food intake alone.2,3 Weight loss is the symptom most commonly associated with cachexia but there are numerous other features (Table 1),1 of which fatigue is an important one (70–100% of cancer patients).4 Cancer cachexia is common. Half of all patients with cancer lose some body weight; one-third lose more than 5% of their original body weight and up to 20% of all cancer deaths are caused directly by cachexia (through immobility, cardiac/ respiratory failure).5 Cachexia is particularly prominent in solid tumours of the upper gastrointestinal (GI) tract and lung (Table 2). Weight loss is a prognostic factor in the survival of cancer patients and is associated with a reduced response to chemoradiotherapy.2