stochastic model for tumor control probability effects of cell cycle and asymmetric proliferation background estimating the required dose in radiotherapy is of crucial importance since the administrated dose should be sufficient to eradicate the tumor and at the same time should inflict minimal damage on normal cells the probability that a given dose and schedule of ionizing radiation eradicates all the tumor cells in a given tissue is called the tumor control probability tcp and is often used to compare various treatment strategies used in radiation therapymethod in this paper we aim to investigate the effects of including cellcycle phase on the tcp by analyzing a stochastic model of a tumor comprised of actively dividing cells and quiescent cells with different radiation sensitivities moreover we use a novel numerical approach based on the method of characteristics for partial differential equations validated by the gillespie algorithm to compute the tcp as a function of timeresults we derive an exact phasediagram for the steadystate tcp of the model and show that at high clinicallyrelevant doses of radiation the distinction between active and quiescent tumor cells ie accounting for cellcycle effects becomes of negligible importance in terms of its effect on the tcp curve however for very low doses of radiation these proportions become significant determinants of the tcp we also present the results of tcp as a function of time for different values of asymmetric division factorconclusion we observe that our results differ from the results in the literature using similar existing models even though similar parameters values are used and the reasons for this are discussed