Cancer has become the leading cause of death for Americans. The development of prognostic tools could have immediate impact on the lives of millions of cancer patients. We have developed an integrated model that includes a cellular model for cell dynamics (cell growth, division, death, and cell adhesion), an intracellular protein regulatory network for cell cycle control, and extracellular reaction-diusion chemical dynamics. This model has produced tumor growth dynamics that agree with tumor spheroid experiments. The model has the potential to be a comprehensive and predictive model for tumor development and chemotherapy based on quantitative experiments.