Analysis of experimental liver metastasis from tumors inoculated in the mouse stomach cavity

Purpose. This study was conducted to develop a patient-like hematogenous metastatic model of gastric-cancer in order to gain an understanding of the tumor biology and to search for new methods of treatment. Methods. We established a natural and easily reproducible liver metastasis model by orthotopic gastric inoculation in Balb/c mice, using the syngeneic tumor, colon 26. Results. This model allowed us to evaluate the effect of partial gastric resection with excision of tumor nodules on the formation of experimental liver metastases from the stomach cavity. Mice given partial gastrectomy showed less metastatic ability than control mice. In these experimental groups, liver metastasis was observed in the only group of mice that died of local tumor regrowth due to incomplete resection of the primary tumor. It is suggested that a period of at least 10 days is required for the formation of liver metastases after tumor inoculation into the stomach cavity. There was no significant increase in the number of liver metastases following splenectomy, or after the administration of anti-asialo GM1 antibody or silica. Conclusion. This experimental model of liver metastases will provide a useful means of understanding tumor biology and the regulation of liver metastases by host immunocompetent cells, and for assessing new therapeutic agents.