Tumour growth and nitrogen metabolism in the host (Review).

Tumour growth is frequently associated with massive loss of body weight and negative nitrogen balance leading to cachexia, one of the worst features of malignancy accounting for nearly two thirds of cancer deaths. At the metabolic level, cachexia is associated with depletion of body lipid stores as well as loss of skeletal muscle protein, which is manifested as an excessive nitrogen loss. The present study reviews the modulations of nitrogen metabolism in tumour-bearing conditions. In addition, the role of different mediators (such as cytokines) in the development of protein wasting is discussed. Particular emphasis has been given to tumour necrosis factor-alpha (TNF-alpha) which seems to have a key role in mediating changes related to nitrogen metabolism in the tumour-bearing host.