Antimetastatic effect by Juzen-taiho-to in the liver metastasis model of colon 26-L5 carcinoma

We investigated the inhibitory effect of Juzen-taiho--o in an experimental liver metastasis model, by means of inoculation of a highly liver-metastatic variant (L5) of murine colon 26 carcinoma cells into the portal vein. Oral administration of Juzen-taiho-to before tumor inoculation resulted in the dosedependent inhibition of liver tumor colonies. Oral administration of Juzen-taiho-to for 7 days before tumor inoculation led to a significant reduction in the number of metastatic colonies and liver weight even in NK-depleted mice as well as normal mice, but not in macrophage- deficient mice. This finding shows that the inhibition of metastasis by Juzen-taiho-to is associated with macrophage function.