Significant work has been done modeling cancerous tumor growth and response to therapy under certain simplifying assumptions, specifically, the assumption of spatial homogeneity. We have chosen a spatially heterogenous model for cancer cell growth using a hybrid Lattice-Gas Cellular Automata method. Cell mitosis, apoptosis, and necrosis are explicitly modeled along with the diffusion of nutrients and a necrotic signal. The model implementation is verified qualitatively and is modified to execute on a parallel computer.