Method for quantitating tumor cell removal and tumor cell-invasive capacity in experimental metastases

An improved method is presented for analyzing the decay of i.v.-injected labeled tumor cells in the lung. A simple compartment analysis yields quantitative values for (a) the rate at which tumor cells are lost or cleared from the lung, and (b) the "invasion" rate at which tumor cells colonize the interstitial space. Statistical methods are outlined for testing the significance of the contribution of each rate to the overall shape of the decay curve and for testing whether or not a given rate is altered significantly during an experiment. The usefulness of the method is demonstrated in analysis of experiments involving perturbations of the host or of the injected tumor cells.