Irradiating the heart leads to the development of fibrosis, which stiffens it, and this in turn leads to problems in the relaxation of the left ventricle. Due to this, blood flow from the lungs into the heart is hindered, and this can cause pulmonary damage. However, after treatment with captopril, the researchers observed an improvement in ventricular relaxation in the irradiated hearts.
Dr Van der Veen and her colleagues are now collaborating with a research group from the Mayo Clinic, Rochester, Minnesota (USA), in order to design a randomised clinical trial where patients who are treated with radiation to the thoracic area including the heart will be treated with either an ACE inhibitor or a placebo after irradiation.
Much progress has been made in radiation treatment over recent years, but in breast cancer, for example, most women still receive high doses to the heart, and this is known to increase the risk of heart disease. A recent study  has shown that for each Gray (Gy)  of radiation, there is a 7.4% increase in the occurrence of a subsequent major coronary event.
"Given that most women will receive a dose of between 1 and 5 Gray, and that the dangers are even greater for women with existing cardiac risk factors or coronary disease, this is still a big problem," said Dr Van der Veen.
Rats were chosen for the study because, unlike mice, they are big enough for researchers to be able to irradiate different part of the lungs and heart. The researchers believe that the way in which ACE inhibition works in both animals and humans is similar.
"We are confident that our clinical trial will see the same protective effect in humans as that which we have seen in rats," said Dr Van der Veen. "We will also now begin to study the late effects of ACE inhibition on RILT to see whe
|Contact: Mary Rice|
European Society for Radiotherapy and Oncology (ESTRO)