Mediastinal irradiation can improve outcome for a wide range of neoplasms, including that of the lungs, breasts and oesophagus as well as lymphomas such as Hodgkin’s disease. However, when the irradiation field includes the heart, untoward late cardiac effects can develop that were underappreciated in the past. Indeed, until the mid 1960s, the heart was thought to be a relatively radioresistant organ.1 Even as recent as the 1980s, the issue of whether radiation exposure led to coronary artery disease was controversial and a relationship was not established until the mid to late 1990s. It was then becoming clear that the cardiovascular risks of mediastinal irradiation may limit the survival benefit in some cancer patients.

Radiation induced heart disease (RIHD) encompasses a range of deleterious effects on the heart, from subclinical histopathological findings to overt clinical disease. The damaging cardiac effects may be manifested in the pericardium, myocardium, valves, conduction system or coronary arteries. Although the cumulative incidence of RIHD is difficult to estimate due to long latency periods from exposure to clinical manifestations, the incidence of coronary heart disease following radiation appears to be greatest when radiation is given for Hodgkin’s disease. This may be due to many years of follow-up leading to a greater chance for detecting disease, since these patients generally received mediastinal irradiation at a young age.2 Survivors of left sided breast cancer who have received mediastinal irradiation have also experienced increased mortality from cardiovascular causes, particularly when the irradiation field included the internal mammary glands resulting in higher dose volumes of irradiation. Mediastinal irradiation for thymomas and oesophageal and lung cancers has also been associated with cardiotoxicity. As oncologic treatment continues to improve with longer survival rates, and the indications for mediastinal irradiation as primary and adjuvant therapy rise, RIHD is likely to be …