A stochastic model for the origin and treatment of tumors containing drug-resistant cells.

A stochastic model for the chemotherapy of experimental tumors is presented. The focus of this model is on the presence of drug-resistant mutants and their influence on eventual treatment outcome. Equations are derived for the joint probability-generating function for the number of chemo-sensitive and chemo-resistant cells. The model is extended to two drugs and it is shown how the model may be used to make deductions regarding the optimum scheduling of therapy.