Radiotherapy treatment for breast cancer can cause heart disease in the long run. The risk of heart disease depends on the dose of radiation and the presence of pre-existing cardiac risk factors, according to a recent study.
Radiotherapy is effective in reducing recurrences of breast cancer. However, the radiation has been associated with increased incidence of heart disease, which may also result in death in some cases. A study published in the New England Journal of Medicine studied some of the factors that could increase this risk.
AdvertisementThe study was conducted in Sweden and Denmark on women who received radiation treatment for advanced breast cancer. The number of women who suffered heart attack or died due to a heart attack, or had to undergo procedures like angioplasty was recorded.
The researchers found that the time interval for the development of heart disease following breast cancer varied among different women. Around 44% instances of heart disease were detected less than 10 years after the cancer was diagnosed, 33% occurred between 10 and 19 years, and 23% occurred 20 or more years later.
Women who received radiation to the left breast had more chances of heart disease as compared to women who received radiation to the right breast. Since the heart is on the left side of the chest, it was more exposed to the radiation directed to the left breast. The chances of heart disease was also more common in women with other health conditions like circulatory diseases, diabetes, lung disease, increased weight, as well as those who smoked or took regular painkillers.
An important finding of the study was that the rate of heart disease increased with increasing dose of radiation. This increase was estimated at 7.4% per gray.
The researchers also found that the risk of heart disease increased within the first 5 years of radiation and continued for at least 20 years.
The study thus indicates that women receiving radiation therapy are at a higher risk of developing cardiac events like heart attack. The risk is higher with higher doses and in women at prior risk of heart disease. This should be taken into consideration in women undergoing radiation therapy for breast cancer and the benefits of the treatment in preventing recurrence of the cancer should be weighed against the risk of developing heart disease.
Risk of Ischemic Heart Disease in Women after Radiotherapy for Breast Cancer; Sarah Darby et al; N Engl J Med 2013; 368:987-998.