Radiation-related heart toxicity

The radiotherapy of thoracic cancers exposes the heart to late radiation-induced complications. The physiopathological and clinical consequences of heart irradiation have been mostly studied in patients with Hodgkin lymphoma and breast cancer. The main cause of cardiac morbidity is radiation-induced coronaropathy with a relative risk estimated between 2 and 3 in earlier studies. Preexisting factors of cardiovascular risk, including chemotherapy, potentalize the cardiotoxicity of radiotherapy. Conformational radiotherapy, adapting the ballistics and the energy to the delineated volumes while carefully evaluating the dose-volume distribution in the organs at risk, allowed a drastic reduction in cardiac mortality. This toxicity no longer seems to be significant if the cardiac volume has received less than 30 Gy. Nevertheless, the prolonged life expectancy of cancer patients and the expanding use of new cardiotoxic anticancer drugs underline the persistent need to further reduce the dose delivered to the heart. Indeed, 1 Gy added to the mean heart dose would increase the cardiotoxic risk by 4% (IC 95%: 2-6%, P=0.0002). A strengthened collaboration between the radiation oncologist and the cardiologist aims at detecting and treating long-term complications after thoracic radiotherapy.