Nutrition and Cancer
A profound state of malnutrition, the cachexia of malignancy, is frequently the most debilitating feature of this disease process. In many instances, it can be attributed to anorexia with an associated distortion of taste sensation or acquired aversion to specific foods, particularly meat. There are, however, patients in whom the extent of weight loss far exceeds the deficit in quantity and quality of calories consumed. In addition to the loss of adipose tissue and protein stores, these patients have a marked degree of insulin resistance with abnormal glucose tolerance. It has been demonstrated that malignancies can cause an augmentation of hepatic and renal gluconeogenesis secondary to enhanced Cori cycle activity, as well as an excessive utilization of fatty acids as metabolic fuel, which can theoretically contribute to a net energy loss by normal tissue. Hyperalimentation with total parenteral nutrition (TPN) with solutions based on 50 percent glucose and mixtures of essential amino acids and vitamins, containing about 3000 calories per day, is used to restore nutritionally depleted patients who have a chance for tumor control by surgery, chemotherapy, and/ or radiotherapy. TPN through a catheter placed in the superior venacava is also indicated in patients with pain on deglutition, fistulas, or intestinal obstruction. When possible, oral hyperalimentation is preferred and effective. TPN in patients who have lost 10 lb or more body weight is associated with an average weight gain of 6 lb in a mean of 24 days, even when chemotheray and radiotherapy are given simultaneously. There is no evidence that TPN preferentially enhances tumor growth. Catheter-related sepsis occurs in about 2 percent of patients. Hyperosmolar, nonketotic coma can be avoided with gradual increases in the concentration of glucose.