Long-Term Cardiovascular Mortality After Radiotherapy for Breast Cancer

ObjectivesThis study sought to investigate long-term cardiovascular mortality and its relationship to the use of radiotherapy for breast cancer.BackgroundCardiovascular diseases are among the main long-term complications of radiotherapy, but knowledge is limited regarding long-term risks because published studies have, on average, <20 years of follow-up.MethodsA total of 4,456 women who survived at least 5 years after treatment of a breast cancer at the Institut Gustave Roussy between 1954 and 1984 were followed up for mortality until the end of 2003, for over 28 years on average.ResultsA total of 421 deaths due to cardiovascular diseases were observed, of which 236 were due to cardiac disease. Women who had received radiotherapy had a 1.76-fold (95% confidence interval [CI]: 1.34 to 2.31) higher risk of dying of cardiac disease and a 1.33-fold (95% CI: 0.99 to 1.80) higher risk of dying of vascular disease than those who had not received radiotherapy. Among women who had received radiotherapy, those who had been treated for a left-sided breast cancer had a 1.56-fold (95% CI: 1.27 to 1.90) higher risk of dying of cardiac disease than those treated for a right-sided breast cancer. This relative risk increased with time since the breast cancer diagnosis (p = 0.05).ConclusionsThis study confirmed that radiotherapy, as delivered until the mid-1980s, increased the long-term risk of dying of cardiovascular diseases. The long-term risk of dying of cardiac disease is a particular concern for women treated for a left-sided breast cancer with contemporary tangential breast or chest wall radiotherapy. This risk may increase with a longer follow-up, even after 20 years following radiotherapy.