Effects of enteral and parenteral nutrition on tumor response to chemotherapy in experimental animals.

The effects of oral and intravenous nutrition on host and tumor responses to graded doses of methotrexate (MTX) were evaluated in 150 adult Sprague-Dawley rats. All animals were inoculated with Walker-256 carcinosarcoma and were fed a regular diet for ten days before assigning them to three dietary groups. Group I (n = 64) received a constant intravenous infusion of 30% dextrose-5% amino acids (IVH), group II (n = 64) received an identical solution orally ad libitum, and group III (n = 22) received a regular diet ad libitum. Animals in groups I and II were then divided into three subgroups each that received either 20 mg/kg, 40 mg/kg, or 60 mg/kg of MTX intramuscularly. Ten days later, all surviving animals were killed. Animals fed the 30% dextrose-5% amino acid diet orally and given 20 mg/kg and 40 mg/kg of MTX lost slightly less body weight when compared with their IVH counterparts. In the 60 mg/kg treatment group, orally fed animals lost 52 gm of body weight compared with 23 gm in IVH animals. IVH rats given 20 mg/kg and 40 mg/kg of MTX demonstrated significant inhibition of tumor growth and decreased tumor weight/body weight ratios when compared with orally fed rats. No improvement in tumor response to 60 mg/kg of MTX was observed, however, when IVH animals were compared with orally fed rats. In a second study, nutrient intake was maintained at a constant level by intravenous infusion in one group and intrajejunal infusion in another group of tumor-bearing rats. Host and tumor responses to 20 mg/kg of MTX were similar in both groups of animals.