Radiation-induced ischemic heart disease
Radiation therapy is a widely used treatment for malignant neoplasms of the chest. Radiation-related cardiovascular disease is associated with significant morbidity and mortality. This review discusses the diagnosis and treatment of radiation-induced coronary artery disease. The most common indications for radiotherapy to the mediastinal region are Hodgkin>s lymphoma and breast cancer. Hodgkin>s lymphoma is one of the most common forms of malignant neoplasms in young people, with an estimated incidence of 3 per 100 000 population and a 10-year survival rate of more than 80%. The incidence of radiation-induced coronary heart disease is about 60% among survivors with Hodgkin>s lymphoma 40 years after radiation therapy, and the risk of coronary heart disease and myocardial infarction is 3.2 and 2 times higher, respectively, compared to the general population. Breast cancer is the most common form of malignant neoplasm among women. In 2017, a meta-analysis was published evaluating the effect of radiation therapy for breast cancer on the risk of coronary heart disease and cardiac death. Radiation therapy for breast cancer was associated with an increase in the absolute risk of 76.4 (95% CI 36.8-130.5) cases of coronary heart disease and 125.5 (95% CI 98.8-157.9) cases cardiac death per 100 000 person-years. The risk began to increase during the first decade for death from coronary heart disease and from the second decade for overall death from cardiovascular disease. There is a time lag between exposure to radiation therapy and the development of coronary artery disease. In survivors of Hodgkin>s lymphoma, the average time to develop coronary artery disease can range from 2 to 40 years, and in patients with breast cancer, about 9-10 years. Risk factors for radiation-induced coronary artery disease include age at the time of radiation therapy, total radiation dose, amount of tissue exposed, and lack of cardiac shielding techniques.