Radiation Raises Risk of Heart Disease in Women Treated for Breast Cancer
A population-based case control study of major coronary events in 2,168 women who underwent radiotherapy for breast cancer between 1958 and 2001 in Sweden and Denmark found a direct link between radiation dose and the occurrence of ischemic heart disease years later.
Study Details
The study, reported in The New England Journal of Medicine, included 963 women with major coronary events sometime after their cancer therapy and 1,205 controls. The researchers analyzed patient data from hospital records, including radiotherapy charts, to estimate the mean radiation doses to their hearts and found that the risk of major coronary events increased as the amount of radiation received by the heart increased.
The overall average of mean doses to the heart was 4.9 Gy, and the rates of major coronary events increased linearly with the mean dose to the heart by 7.4% per gray, with no apparent threshold. The risk started within the first 5 years after radiotherapy exposure and continued for at least 20 years. While the relative risk for heart disease was similar for both women with and women without cardiac risk factors at the time of radiotherapy, those with preexisting cardiac risk factors or established heart disease had a greater absolute higher risk. That increased risk was modest, however.
Bottom Line
According to the study, a 50-year-old woman with no preexisting cardiovascular risk factors and a mean radiation exposure of 3 Gy has a 2.4% increased risk of dying from ischemic heart disease before the age of 80, compared to 1.9% for patients of the same age with breast cancer who have not undergone radiation therapy.
The results, said the study authors, will help physicians estimate a patient’s potential risk for radiation-related heart disease and determine the best course of treatment.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
