Stochastic modeling and validation of growth saturation and radiotherapeutic response of multicellular tumor spheroids.

An advanced three-dimensional (3D) Monte Carlo simulation model of both the avascular development of multicellular tumor spheroids and their response to radiation therapy is presented. The model is based upon a number of fundamental biological principles such as the transition between the cell cycle phases, the diffusion of oxygen and nutrients and the cell survival probabilities following irradiation. Predicted histological structure and tumor growth rates evaluated for the case of EMT6/Ro spheroids have been shown to be in agreement with published experimental data. Furthermore, the underlying structure of the tumor spheroid as well as its response to irradiation satisfactorily agrees with laboratory experience.