Currently, breast cancer is one of the main problems of medicine, from which a significant number of women around the world constantly die. Therefore, its detection becomes important, that is, the detection of malignant breast tumors in the early stages is the main task. In recent years, the use of thermal imaging techniques to identify and differentiate the stages of breast cancer has aroused exceptional interest. Microwave (RMT) and infrared (IR) radio-thermometric imaging techniques are very useful for preclinical assessment because these methods are relatively fast and can be reused over a longer period without the risk of exposure. Some studies show that microwave radio thermometry, when used with well-defined protocols, can detect the first symptoms of cancer several years earlier than mammography. This method allows for diagnosis in women of any age and allows for periodic screening programs in countries with any level of resources. Thus, this method can be considered as a good alternative to mammography. This chapter proposes a model for the identification of a malignant breast tumor based on thermogram data obtained using microwave radio-thermometry.