The University of Manchester has reported that new research has found radiotherapy treatment for lung cancer could have a negative effect on the health of the heart. Scientists from the University of Manchester’s Division of Cancer Sciences and the Christie NHS Foundation said it could reduce survival rates in people receiving the therapy by up to 20%.

Radiotherapy plays a major role in curative-intent treatment of lung cancer and advances in radiation technology have enabled doses to be delivered to a larger proportion of patients. However, over the past two years, evidence has emerged showing radioactivity of the heart from radiotherapy is increasing mortality rates.

Dr Alan McWilliam, who led this research which is published in the European Journal of Cancer, said “The effect of radiation on the heart for patients treated with radiotherapy is not well understood at all, that is why we have carried out this initial study. We found that the radiation may cause an extra burden on the heart and even small amounts of radiation may have an effect. We have identified the top of the heart in particular as a dose-sensitive region, where excess dose results in poorer patient survival.”

He said people receiving a higher dose of radiotherapy to this region of the heart have a 20% higher risk of early death than those getting a lower dose. One of the key reasons for such high numbers in people with lung cancer is that their tumours can often be much closer to the heart than other forms of cancer. This means some radiation will inevitably hit the organ, having an adverse effect.

Alan McWilliam said “The effect of radiation on the heart for patients treated with radiotherapy is not well understood at all, that is why we have carried out this initial study.This is especially true when compared to other patients groups, such as breast cancer and lymphomas, who are also usually younger and healthier than those suffering with lung cancer. These are patients who have poor cardiac health and conditions such as heart disease which also contribute to the problem.”

The researchers analysed eleven thousand people, looking at where in the heart there was radiation and how long the patients survived. They identified that the top of the heart in particular as being more sensitive to radiation than the body of the organ. The testing showed a highly significant region across the base of the heart, where higher doses were associated with worse patient survival.

To carry out the study, a high resolution, normal tissue dosimetric analysis was performed. This helped identify regions in the heart that correlated with poorer survival. However, the team’s research and analysis only highlights the top of the heart as important. The next step is to further this work and do clinical studies to investigate clinical causes and ways to combat the issue.