Combined hyperthermia-radiotherapy (CHR) exploits a feedback mechanism between heat and radiation: elevated tumor temperature enhances radiosensitivity, altering the dose-response relationship in ways that other clinical tools do not capture. This project develops a coupled mathematical model and simulation environment that integrates three interdependent components: a thermal model governing temperature distribution and its effect on tissue radiation properties; a transport model estimating dose deposition as a function of local temperature; and a biological response model describing tumor behavior under simultaneous heating and irradiation. The goal is a simulation framework that realistically predicts treatment outcomes for recurrent tumors undergoing CHR, supporting more accurate treatment planning.