Heating the tumor tissue with an optimized amount of microwave energy is a promising combinational therapy, called hyperthermia treatment (HT), used with chemotherapy and radiotherapy. This combinational therapy has shown improvement in the survivorship for patients, and life after treatment. In clinical practice, radiation oncologists are still not using HT as a standard therapy because of some side effects like toxicity and hotspots on the surrounding site. To address this issue, optimal focusing of microwave on tumors, with minimal damage of surrounding tissues, is essential to avoid the side effects of HT. Our article briefly discusses on optimal focusing of microwaves on a tumor, computational feasibility study, and analysis of hyperthermia treatment. For the achievement of best outcomes, electrostatic modeling and heat flow modeling of 2D female breast models with tumors have been carried out. The finite element method (FEM) is used to solve the bio-heat equation at the tumor domain, consisting of radiation and convection-based boundary conditions. Obtained simulation results show that the highest focusing of radiation power on and around the tumor inside the breast has been given higher efficiency for hyperthermia. Our 2D modeling simulation results are helpful for improving hyperthermia treatment of breast cancer patients, with minimal damage to cells in the surrounding. Also, the article includes a mathematical analysis of hyperthermia and FEM modeling results concerning temperature distribution, heat flow, electric field intensity, electric flux density, heat flux density, and temperature variations in the breast tumor.