Nutritional changes in patients with cancer.

At some time during the clinical course of any patient with metastatic malignant disease, one frequently sees the symptom complex of anorexia, asthenia, loss of body tissues and inability to conserve normal regulatory functions. This common host response bears no positive correlation to the amount, type of site of neoplastic tissue and patients may have obvious widespread tumors without such manifestations. However, when this systematic response occurs, it is readily recognized by the clinician experienced in this area that uncontrolled tumor growth is occurring and that unless such cancerous growth can be inhibited, progressive inanition and ultimate death will occur. Studies designed to define the metabolic changes that are present in the above clinical syndrome must take into account the subnormal nutritional status of such patients. Since anorexia is invariably present, the stoichiometric regulation and metabolic adaptions which are normally seen with restricted protein and caloric intake have been the subject of consideration. Semistarvation normally results in diminished adenosine triphosphate (ATP) requirement, since the formation of glycogen, fatty acids and triglycerides which result from transient excesses of foodstuffs are diminished. This in turn leads to a decrease in oxygen consumption. While transient increase in gluconeogenesis may be seen, the long term adjustment is that of increased mobilization of fatty acids from adipose tissue with diminished glucose production from amino acids.’ Conservation of the latter ingredient primarily for key enzyme synthesis is necessary for survival (e.g. those enzymes related to fatty acid oxidation). A considerable amount of older work has suggested that the normal decrease in oxidative metabolism does not take place in patients with cancer.2.3 Calculations of energy expenditure, determinations of basal oxygen consumption and CO2 production all seem inappropriately high for the condition of study. In a control series vs five subjects with metastatic malignant disease, the total mean CO2 production in the basal state was 7.6 mm/kg/hr vs 8.3 mml/kg/hr (malignant disease). Viewing the data as such, the mean difference between the two groups is only 10% and of little significance. Yet all subjects in the neoplastic group, though roughly matched in weight to the control group, had lost body weight and had lower caloric intakes at the time these studies were done. When viewed in this context, i.e. the nutritional status of the patients, the data become more meaningful. Studies of the metabolic mixture resulting in CO, production, however, show that normal proportions of glucose and fatty acid are oxidized in the fasting state.4 New glucose production in the postabsorptive state, as determined by tracer technique, has shown a mean value of 5.9g/hr for the control group and 6.6g/hr in the group with cancer.’ Even though the latter group tended to have lower body weights, new glucose production, presumably largely from amino acid precursors, was comparable or slightly enhanced over that of the control group. Normally about 17% of the lactate produced by glycolysis is reconverted into glucose.