Host and tumor responses to increasing levels of intravenous nutritional support

Responses of tumor and host to increasing rates Of intravenous infusion of nutritional substrate remain undefined. Growing Fischer 344 rats underwent sarcoma transplant (day 0), aseptic placement of a superior vena cava catheter (day 14), and infusion with a nutritionally adequate solution (days 18 to 28). Rates of infusion (percentage of normal caloric intake) were 33%, 67%, 100%, 133%, and 167%. Controls included a tumor-bearing (T) group fed an identical solid oral diet and non-tumor-bearing rats treated identically to T rats. At least five of six rats survived the 10-day experiment from each group except the T-167% group, none of which survived. The mean tumor weight, carcass weight, ratio of tumor weight: carcass weight, and ratio of tumor weight: lean body mass increased linearly with the rate of substrate infusion. Composition studies of tumor revealed similar content of protein, fat, and water for all tumors. Studies of carcass composition revealed an increase in rate of fat accumulation and a constant rate of protein accumulation with increase in substrate infusion. These data indicate that tumor growth increases to a greater extent than the lean host carcass with increasing rate of substrate infusion and that high levels of substrate infusion are not tolerated.