Radiation increased risk for cardiovascular events later in life

Women who underwent radiation during breast cancer treatment carried an increased risk of more than 7% for later cardiovascular events, according to study results.

Researchers conducted a population-based case-control study of myocardial infarction, coronary revascularization or death from ischemic heart disease in a cohort of 2,168 women who received radiotherapy for breast cancer.

Eligible participants underwent surgery between 1958 and 2001 in Sweden and Denmark. The study group included 963 women who experienced one of the coronary events, and 1,205 who served as controls.

 

Sarah C. Darby

Sarah C. Darby, PhD, of the University of Oxford, and colleagues evaluated the mean radiation doses to the whole heart and the left anterior descending coronary artery.

of the University of Oxford, and colleagues evaluated the mean radiation doses to the whole heart and the left anterior descending coronary artery.

Overall, the average mean dose to the whole heart was 4.9 Gy (range, 0.03-27.72).

A linear association with no apparent threshold was observed between mean dose to the heart and rates of coronary events. Events increased by 7.4% per Gy (95% CI, 2.9-14.5).

Increases began within 5 years of radiotherapy treatment and continued for three decades.

Women with or without cardiovascular risk factors at the time of radiation experienced similarly increased risks.

“Exposure of the heart to ionizing radiation during radiotherapy for breast cancer increases the subsequent rate of ischemic heart disease,” the researchers concluded. “Women with pre-existing cardiac risk factors have greater absolute increases in risk from radiotherapy than other women.”

Reference:

Darby SC. N Engl J Med. 2013;368-987-998.