A complication of radiation treatment in the thoracic region affecting the tissues of the heart.
Radiation induced heart disease occurs as a result of radiotherapy treatment causing acute inflammation and progressive fibrosis of the pericardial, myocardial, and endocardial tissues. This damage can manifest acutely as pericarditis, and chronically as congestive heart failure, myocarditis, valvular stenosis and regurgitation, fibrosis of the conduction system, ischemia, coronary artery disease or myocardial infarction.rr
With significant improvements in cancer treatments leading to increased disease free survival for cancer patients, greater numbers of these patients are subject to this late complication of cancer treatment.
The risk that a patient may have a radiation associated event is life long, and absolute risk appears to increase with length of time since exposure. Radiation-associated cardiovascular toxicity may in fact be progressive.r
Currently, there does not appear to be a safe minimum dose for the heart to reduce the risk of radiation associated cardiac events.rr
Associated risk factors for radiation induced heart disease include:
- prescribed dose of >30-35 Gy to the thoracic regionr
- younger age at time of treatmentr
- doses >2 Gy per fractionr
- increased mean dose to the heartr
- concomitant administration of cardiotoxic systemic agents (e.g. anthracyclines, trastuzumab)r
- history of pre-existing cardiac risk factors.r
Other risk factors include co-morbidities such as diabetes, hypertension, dyslipidaemias and obesity, plus lifestyle factors such as smoking.rr
There is some evidence that risk of radiation induced heart disease has been decreased with the introduction of modern treatment techniques that reduce not only the dose of radiation, but also the volume of heart within the treatment field. This evidence will not be confirmed until a longer follow up time is allowed for.r