Effect of isoflayones genistein and daidzein in the inhibition of lung metastasis in mice induced by B16F‐10 melanoma cells

Two dietary soybean isoflavones, genistein and daidzein, were studied for the inhibition of lung metastasis induced by B16F-10 melanoma cells in C57BL/6 mice. The isoflavone genistein at 200 mumol/kg body wt significantly inhibited (53.6%, p < 0.001) lung tumor nodule formation. The lung collagen hydroxyproline content and the serum sialic acid level, a marker of metastasis, were also significantly lower in these animals than in untreated tumor-bearing animals. Genistein treatment also increased the life span of the tumor-bearing animals (47.7%, p < 0.001). The isoflavone daidzein had no significant effect on the reduction of lung metastasis induced by B16F-10 melanoma cells.