A specific dietary zinc requirement for the growth of Walker 256/M1 tumor in the rat.

To determine the specific effect of zinc status on the growth of Walker 256/M1 carcinosarcomas young male rats were pair-fed either a control or zinc-deficient diet for 14 days, were implanted with tumors and killed 7 days later. Half of the deficient rats were repleted with zinc for the 7 days after tumor implantation. In deficient rats, tumor weights were decreased 70% (p less than 0.005), tumor necrosis was 3-fold greater (p less than 0.05) and tumor zinc concentrations were decreased 23 to 37% (p less than 0.005). A specific zinc effect was observed by a 2-fold increase in tumor weights in repleted rats (p less than 0.05) with marked decreases in tumor necrosis (p less than 0.05) and 29 to 84% increases in tumor zinc concentrations (p less than 0.005). Since there were no decreases in organ weights of zinc-deficient animals and no correlation between final tumor weights and postimplant changes in carcass weights, the results indicate a specific inhibitory effect of zinc deficiency independent of a nonspecific malnutrition.