Breast cancer is one of the leading causes of death among women worldwide, and its incidence has increased in recent years. The treatment of breast cancer requires a multidisciplinary approach, in which surgery, systemic treatments (chemotherapy, hormonal therapy, and/or targeted therapies), and radiotherapy play foundational roles.

Thanks to advancements in breast cancer treatment in recent years, patients’ disease-free and overall survival rates have significantly improved. With the increasing lifespan of patients, it has become even more important to prevent cardiovascular-related side effects and potential risks caused by breast cancer treatment in later years, and to maintain their quality of life.

Radiotherapy is one of the most important components of treatment for breast cancer patients. A large proportion of breast cancer patients require radiotherapy after surgery. Post-surgical radiotherapy has positive effects on disease control in the breast/chest wall and lymph nodes, as well as on patients’ overall survival. However, chemotherapy received for breast cancer and subsequent radiotherapy may increase the risk of cardiovascular diseases, especially in patients with pre-existing heart conditions.

Therefore, minimizing the adverse effects of radiotherapy is a significant challenge for radiation oncologists specialized in this area. In particular, the risk of coronary ischemic disease is higher in patients receiving radiotherapy to the left breast and lymphatics, as well as those receiving systemic treatments (chemotherapy and targeted agents), compared to other patients. Thus, it is essential to be more cautious about heart problems and cardiovascular health in patients with left breast cancer. Thanks to current technological advancements, this previously feared side effect is now less of a concern.

Anatomically, the heart is located just below the left breast, and the coronary artery, the most crucial vessel for heart health and nourishment, lies in front of the heart. During radiotherapy, the high doses received by the heart and this vessel may increase the risk of heart disease in the future. Therefore, modern radiotherapy techniques have been developed to protect the heart and coronary arteries.

Through “breath-controlled treatment,” during breast radiotherapy, the patient’s breathing intervals can be monitored by special systems, allowing the machine to deliver radiation only at the appropriate times while the patient is lying down. This ensures that the heart and the coronary artery are moved out of the radiation field by controlling the breath, reducing their exposure to radiation. As a result, patients can be protected from potential heart diseases in the future by minimizing the dose received by the heart and coronary artery. This approach significantly reduces the risk of heart disease and heart attacks in the remaining life of patients with left breast cancer. Additionally, for patients at risk of coronary artery disease, it is strongly recommended to avoid smoking, control their weight, eat healthily, manage blood lipids, and engage in regular physical activity.