The effects of nutrition and treatment of cancer on host immunocompetence.

Conventional approaches to therapy for cancer, such as chemotherapy, operative therapy and radiation therapy, can produce profound changes in host immunity. The effects of chemotherapy upon immune responses are related both to the dosage and duration of therapy and are readily reversible. Operative therapy likewise suppresses both humoral and cell-mediated immunity for two to three weeks, as manifested by in vitro and in vivo tests of these functions. Radiation therapy, however, seems to decrease host immune responses for more prolonged periods of time, up to ten years. Nutritional status may also affect both limbs of the immune system, and malnutrition is being recognized with increasing frequency as a clinical problem in patients with advanced primary malignant or metastatic disease, especially during antineoplastic therapy. Intravenous hyperalimentation is a safe and effective method for correcting nutritional deficits in patients with cancer; moreover, immunocompetence may be enhanced during adequate nutritional rehabilitation.