Nutrition and cancer: physiological interrelationships.

There are many tumors that have paraneoplastic syndromes. Furthermore, location of certain tumors can result in very specific effects on the host, especially tumors in the hypothalamus, the intestinal tract, or the liver. Finally, tumors of the immune system can have significant distant consequences. However, from direct experimental evidence, from model systems, and from the utilization of nutritional manipulation in the treatment of cancer, the data suggest very strongly that there is no unique cancer malnutrition. Early diagnosed cancer does not show malnutrition as a presenting symptom. Furthermore, all metabolic disturbances can be explained on the basis of the metabolic differences of tumor cells and normal cells and are very frequently proportional to the bulk of the tumor. The cachexia that is associated with malignancies is more likely cachexia in cancer patients than it is a specific cancer cachexia, unless the tumor burden is very large. This point was clearly made in a short review of the causes of cachexia in nearly 1500 cancer patients in Russia (145). Brennan also feels that most cases of malnutrition are uncomplicated starvation, and cancer cachexia has many features seen in major injury or sepsis (16). This distinction has great implications in the management of cancer patients.