Radiation exposure for every gray (GY) to the heart, the risk of major heart events rose by an average of 7.4 percent – with no apparent threshold, says Sarah Darby, of the clinical Trail Service Unit in Oxford, England, who conducted a study of 2,168 breast cancer survivors in Sweden and Denmark. However, the rate varied over-time with a 16.3% greater risk in the first 5 years after exposure and 15-5% in the second 5 years. The rate fell to 1.2% in the second decade and rebounded in later years to 8.2%.
Women with pre-existing heart risk factors were more vulnerable to later coronary problems, doctors said.
The increased risk was greatest during the first five years after radiation treatment but remained for at least two decades. Women with pre-existing cardiac risk factors experienced an even greater risk, according to ABC News. While radiation provides value for breast cancer patients, “clinicians may
wish to consider cardiac dose and cardiac risk factors as well as tumor control when making decisions about the use of radiation.”
Radiation is a key weapon in the fight against early breast cancer and doctors work hard to restrict the radiation to the area of tumor growth. But it can be difficult to limit exposure to just the tumor and nearby tissue.
There are few women for whom carefully planned radiotherapy using standard techniques would cause a substantial increase in the risk of heart disease if radiotherapy is given in the usual way, according to researchers.