Wasting in gastrointestinal tract cancers: clinical and etiologic aspects.

One of the major complications found in patients affected by malignancy of the gastrointestinal tract is represented by an alteration of nutritional status, up to real cachexia. The factors responsible for the severe nutritional deficiencies are: metabolic alterations, which involve carbohydrate, lipid and protein metabolism; the reduced availability of nutritional substrates, due to neoplastic growth that, by expanding locally or destroying the affected organ, determines alterations of deglutition, digestion and food absorption; the effects of surgical therapy, radiotherapy and chemotherapy, which are able to cause temporary or permanent nutritional deficiencies; the effects of immunological mediators, and above all of tumor necrosis factor-alpha (TNF-alpha). In fact, TNF-alpha is considered the main mediator of cancer cachexia as it is responsible for different metabolic alterations, both directly and by the activation of other mediators, such as lipid mobilizing factor (LMF) and protein mobilizing factor (PMF). In addition, a negative energy balance in cancer patients could occur as a consequence of increased energy requirements. In this connection, patients with different neoplasia localisation, show high or within the normal range energy expenditure values. These data indicate that the increase in energy metabolism is not likely to represent the main determining factor in neoplastic cachexia. In conclusion, since patients affected by malignancy of the gastrointestinal tract showed a reduction in body weight, fat and fat-free mass, accurate evaluation of nutritional status should be useful in the management and follow-up of these patients.