Despite current research in the development of drug-based cytostatic and targeted therapies in the treatment of breast cancer, radiation therapy (RT) is an important component in the treatment of this pathology in the postoperative period. At the same time, an important problem is the development of pathological changes in the heart in the long-term period, which worsen the quality of life and increase the risk of cardiac death 10 or more years after RT The problem of heart damage due to RT is gaining new significance due to the existing increase in the number of cancer patients requiring radiation exposure in the modern world. RT of malignant tumors of the breast and organs of the chest cavity causes damage to all structures of the heart, including the coronary arteries, valves, conducting system, pericardium. The frequency of heart damage increases in proportion to the time that has passed after RT. According to some authors, the prevalence of clinically significant radiation-induced heart diseases 5–10 years after RT is 10–30 %, and the frequency of asymptomatic lesions is 88 %. The duration of the latent period can reach 15–20 years. The work has an analysis of long-term studies of the presence of pathological changes that are found in the heart tissues of patients with breast cancer, as a result of radiation therapy. Key words: breast cancer, radiation therapy, adjuvant radiation therapy, radiation damage to the heart.