The effect of an acute fast on human head and neck carcinoma xenograft. Growth effects on an 'isolated tumor vascular pedicle' in the nude rat.

The effects of nutritional state on tumor growth are poorly understood. Most animal studies to date suggest an inhibitory effect of nutritional depletion on tumor growth and a stimulatory effect of nutritional repletion or overfeeding. We have modified an "isolated tumor vascular pedicle" model in the nude rat to study the growth and tumor-specific nutrient utilization of the FaDu cell line of human hypopharyngeal squamous carcinoma. Two weeks after tumor implantation, rats were randomized to either a fed or fasted study group for an additional 7 days. Tumors were significantly larger in the fasted group (0.602 +/- 0.215 g vs 0.362 +/- 0.104 g; P < .02). Whole blood nutrient gradients were determined across the tumor and systemic tissues in both groups. The nutrient gradients across these tissues were significantly different in the fed animals and approached statistical significance in the fasted animals. In addition, there appeared to be a greater utilization of glucose in the fed group (-0.401 +/- 0.904 mmol/L vs -0.298 +/- 0.589 mmol/L), while there was a greater production of lactate in the fasted group (0.798 +/- 0.518 mmol/L vs 0.046 +/- 0.639 mmol/L; P < .1). Flow cytometric analysis revealed no difference in the percentage of cells in any particular stage of the cell cycle between the two groups. These results suggest that the maintenance of adequate body weight may be beneficial not only to the nutrition of the cachectic tumor-bearing host but may also prevent a ketotic state or state of lipolysis that may be preferential to the tumor.