Total parenteral nutrition in a methylcholanthrene-induced rat sarcoma model.

Problems with currently available studies of the effects of total parenteral nutrition (TPN) on rat tumor models include: inadequate definition of the natural history of the tumor model; use of nutritional techniques and solutions which have not been proven effective; failure to allow animals to recover from stress of catheterization before starting nutritional manipulation; short-term studies; failure to use sham-operated orally fed control animals; and inadequate evaluation of nutritional result. We have instituted TPN after a 4-day postcatheterization recovery period in a defined methylcholanthrene-induced rat sarcoma model. Preliminary results suggest that TPN increases tumor weight without changing tumor composition of water, nitrogen, or fat. TPN also increases carcass fat and water content, but not carcass protein. In tumor-bearing animals, the percentage of energy expended on activity decreases with increasing tumor burden in both TPN and orally fed controls. TPN in these studies appears to support fat stores and stimulate tumor growth.