Usefulness of Coronary Computed Tomographic Angiography to Evaluate Coronary Artery Disease in Radiotherapy-Treated Breast Cancer Survivors

Abstract

Breast cancer is the most commonly diagnosed cancer in women and radiotherapy is a widely used treatment approach. However, there is an increased risk of coronary artery disease and cardiac death in women treated with radiotherapy. The present study was undertaken to clarify the relation between radiotherapy and coronary disease in women with previous breast irradiation using coronary computed tomographic angiography (CCTA). We conducted a retrospective analysis of women with a history of right or left-sided breast cancer (RBC; LBC) treated with radiotherapy who subsequently underwent CCTA. RBC patients who had reduced radiation doses to the myocardium served as controls. Patients (n = 6,593) with a history of nonmetastatic breast cancer treated with radiotherapy were screened for completion of CCTA; 49 LBC and 45 RBC women were identified. Age and risk factor matched patients with LBC had higher rates of coronary disease compared with RBC patients; left anterior descending (LAD) coronary artery (76% vs 31% [p < 0.001]), left circumflex (33% vs. 6.7% [p = 0.004]), and right coronary artery (37% vs 13% [p = 0.018]). Mean LAD radiation dose and mean heart dose strongly correlated with coronary disease, with a 21% higher incidence of disease in the LAD per Gy for mean LAD dose and a 95% higher incidence of disease in the LAD per Gy for mean heart dose. In conclusion, LBC patients treated with radiotherapy have a significantly higher incidence of coronary disease when compared with a matched group of patients treated for RBC. Radiation doses correlated with the incidence of coronary disease.