Hormonal and metabolic abnormalities in the malnourished cancer patient: effects on host-tumor interaction

Many common metastatic cancers are associated with marked weight loss at the time of diagnosis. Anorexia clearly plays a major role in weight loss in the cancer patient, but cannot explain all of the weight loss noted. Malnourished patients with localized cancers under metabolic ward conditions fail to gain weight when given apparently adequate calories for anabolism, thus suggesting that these patients are hypermetabolic. Increased whole body protein breakdown, increased lipolysis, and increased gluconeogenesis have been repeatedly demonstrated in malnourished cancer patients. Protein and glucose metabolism are closely linked, and both are regulated by a number of the same hormones and metabolites. For example, when increased glucose production in malnourished cancer patients is inhibited pharmacologically, protein catabolism is proportionally decreased. Studies of glucose, growth hormone, cortisol, and insulin secretion following an oral glucose load in well-nourished cancer patients are consistent with insulin resistance but no other hormonal abnormalities. Malnourished cancer patients have elevated levels of growth hormone that are further stimulated by arginine and insulin infusion. No abnormalities of thyroid function were noted in cancer patients. Current studies are underway to determine the mechanisms and effects of progestational steroids and cytokines on both food intake and intermediary lipid metabolism.