Pulmonary and cardiac late effects of ionizing radiations alone or combined with chemotherapy

High doses of ionizing radiation (> 40 Gy) cause severe lung fibrosis in approximately 5% of the cases. There is a twofold increase when chemotherapy is added to ionizing radiation. Lung fibrosis is due to the destruction of lung tissue by ionizing radiation but also to various cytokine effects (PDGF-beta, TGF-beta). Only a minority of patients (approximately 10%) with abnormal X-rays will experience clinical symptoms. The most important radiobiological parameters which accounts for pulmonary tolerance is the fraction size. Irradiation of the heart begets multifarious late sequelae which are often left unrecognized. Chronic pericarditis affects approximately 5% of the patients when the irradiation dose exceeds 40 Gy. Coronary artery disease can be diagnosed in 5 to 10% of the patients. This late complication is more likely to occur if the patient was young at the time of the irradiation or if other risk factors are associated. Valvular defects can be found in 15 to 30% of the patients. However, the mortality rate is very low (0.5%). Finally, conduction defects can also be seen in approximately 5% of the patients. It is very likely that the radiation dose given to the heart should not exceed 30 Gy if late sequelae are to be avoided.