Title: Studies of Ionising Radiation and the Risk of Heart Disease
Funder: Department of Health (England)

Abstract: Background: Recent evidence shows that exposure to ionising radiation can increase the risk of heart disease. Specific exposures that may cause radiation-related heart disease include radiotherapy for cancers such as breast cancer and lymphoma. There may also be an increased risk following some cadiac investigations and procedures, such as coronary CT scans and radionuclide stress tests. As yet, however, there is little information as to the specific types of heart disease that are inducible by such radiation, nor on the magnitude and determinants of the risk. Aims in relation to the issue to be addressed: This research project will obtain new evidence on the extent to which cardiac exposures from breast cancer radiotherapy delivered in the past increase the risk of different types of heart disease and on the way in which risk varies with age at exposure and time since exposure. It will then obtain dose-response relationships in the form of estimates of the proportional increase in risk per unit dose for ischaemic heart disease, pericarditis, and valvular heart disease. Finally it will derive estimates of the absolute risks following future exposure scenarios. Research plan and method of investigation: To carry out an analysis of data on mortality from heart disease in over 2 million breast cancer patients worldwide. To perform case-control studies of the incidence of (i) ischaemic heart disease, (ii) pericarditis and (iii) valvular heart disease in the complete population of women given radiotherapy for breast cancer in Denmark during 1977-2005. To derive dose estimates for the women in the case-control studies, leading to dose-response relationships of the percentage increase in risk per unit dose. To assemble estimates of the absolute risk of developing, and of dying from, various types of heart disease following particular exposure scenarios. Research team: Prof. Sarah Darby PhD, Prof. of Medical Statistics in the University of Oxford will lead the research. Other senior members of the Oxford research team are Dr Paul McGale PhD, Senior Statistician, and Dr Carolyn Taylor FRCR, Clinical Oncologist. Prof. Marianne Ewertz MD DMSc (Doctor of Medical Science), Clinical Prof. and Consultant in Breast Oncology, Odense University Hospital, University of Southern Denmark will be responsible for the collection of data in Denmark. The research team also includes a statistician and a D Phil student (medical statistics) in Oxford, and a data collection team and D Phil student (medical physics) in Denmark. A Consultant Cardiologist and a Prof. of Medical Physics will act as advisors. Potential impact/influence on the relevant policy field, users and wider stakeholders: Our aim is to compile and publish a series of user-friendly tables or charts indicating the absolute risk of radiation-related heart disease following particular exposure scenarios. This will be useful for those formulating treatment guidelines and radiation protection policy. It will also be directly useful in clinical practice where the benefit from radiotherapy and other procedures that involve exposure of the heart will outweigh the risk for some patients but not for others. At the present time, it is difficult for both doctors and patients to balance the risks against the benefits when deciding whether or not a particular procedure would have a net benefit.


Research activity codes: 7.3 MANAGEMENT AND DECISION MAKING
Health categories: CANCER AND NEOPLASMS