Analysis of a bioassay for circulating tumor cells in two murine malignancies: Correlations with tumor age and extent of metastatic disease

Abstract

Analysis was performed in two murine tumor systems of a bioassay for determining the relative concentrations of circulating tumor cells in tumor-bearing animals. Blood obtained from donor mice bearing a methylcholanthrene-induced fibrosarcoma or S-91 melanoma was intravenously injected into paired syngeneic recipient animals. For both tumors, the relative concentrations of circulating tumor cells in the donors were measured by the frequency of embolic pulmonary tumor growths in the recipient mice. The concentrations of circulating malignant cells correlated significantly better with the extent of metastatic disease in the donors than with the size of the primary tumors. It was concluded that the concentration of circulating malignant cells is not dependent upon the extent of primary tumors. It was further concluded that, for the tumors studied, the presence of disseminated disease is correlated with a relatively high concentration of circulating tumor cells.