Malignant disease: nutritional implications of disease and treatment.

Protein-energy malnutrition (PEM) is common in cancer patients and may develop into the syndrome known as 'cancer cachexia'. This is characterised by complex disturbances in carbohydrate, lipid, protein, and electrolyte metabolism. The aetiology is equally complex, with host and therapeutic factors contributing to the reduced food intake and effects on host tissues. Anorexia is of prime importance, differing in its cause from one patient to another and often presenting a barrier to successful nutritional support. Further research is necessary to elucidate the interaction of central and peripheral factors that may be involved in the aetiology of anorexia. Because of the interplay of biochemical, physiological, and psychological consequences of cancer, the nutritional support of the patient presents a considerable challenge to the caring professions.