The interest in magnetic fluid hyperthermia (MFH) and cancer therapy has noticeably increased in the last years. At present, a successful realization of this interdisciplinary research is hampered by some unsolved problems. One of these problems this paper intended to clarify is how to find an estimate of the appropriate dosage of magnetic nanoparticles that injected into the tumor would help achieve an optimum temperature of 42degC, thus resulting in an increase of the susceptibility for apoptosis in tumor cells. We created a computational model in COMSOL: Multiphysics in order to analyze the heat dissipation within the tumor tissue. By considering various types of tissues with their respective physical and physiological properties (breast, liver, and skin tissues) and also by taking into account the amount of heat generated through the Brownian rotation and the Neel relaxation, it has been studied the tumor border temperature achieved for various concentrations of magnetic nanoparticles in their superparamagnetic behavior. Distinct simulations of a spherical tumor located in a cubical region of a volume of 1.2-3.5 cm3 within the tissue were designed. We performed a systematical variation of tumor diameter and particle dosage for every physical parameter of above mentioned tumor tissues (e.g., tissue density, tumor/tissue perfusion rate). By this systematization we intended to understand the interdependence of these parameters and their effects on hyperthermia therapy.