Cancer cachexia in man: a review.
There are many factors which are responsible for the high incidence of cachexia in human neoplasia. In this review, those considered to be of major importance are discussed. Nutritional disturbances, such as anorexia and malabsorption, are common and nutritional repletion may be beneficial to certain patients. Raised metabolic rate and energy expenditure are also encountered. Tumour cells may act as a nitrogen trap or energy sink, but the significance of these mechanisms in man is questionable. Ectopic hormone production by tumours is well established and a number of tumour-derived substances have been described which interfere with the intermediary metabolism of the host. The significance of these various substances also remains uncertain. Most experimental studies of cancer cachexia have utilized transplantable animal tumour models which bear a poor resemblance to the clinical condition. Development of more suitable models with human tumour xenografts might allow a quicker and better understanding of the aetiologies of human cancer-induced cachexia.