An improved discrete-continuum model describing invasion of healthy tissue by tumor cells is presented in this paper. In the model, we focused on three variables implicated in the metastasis process: tumor cells, healthy tissue (extracellular matrix) and matrix degrading enzymes. This is a discrete-continuum model, because the latter two variables are continuous (concentrations) and the tumor cells are discrete (individuals). The continuum part of the model describes the interaction of the chemicals with the extracellular matrix whereas the individual based part focuses on the micro-scale level and controls the cell migration and interaction. This technique enables one to model the migration and invasion at the level of individual cells and hence it is possible to examine the implications of metastatic spread, also with this model we can predict about the metastatic ability of tumor cells and estimate how far an initial tumor cell will invade.

Keywords