(HealthDay News) — Risk of cardiac events is increased by exposure from breast radiotherapy, though contemporary techniques, including lower radiation doses and prone positioning, have helped lower these risks, according to research published online Oct. 28 in JAMA Internal Medicine.
David J. Brenner, Ph.D., D.Sc., of Columbia University in New York City, and colleagues used historical data to estimate contemporary risks of major coronary events caused by radiotherapy for breast cancer.
The researchers found that the current patient-averaged mean cardiac dose was 1.37 Gy for standard supine-positioned radiotherapy, which was less than one-third of the dose reported for treatment during 1958 to 2001. The highest estimated radiotherapy-induced excess risk of major coronary events was seen in women with high baseline cardiac risk receiving left-sided radiotherapy in the supine position (3.52 percent), and the lowest excess risks were seen in women with low baseline risk receiving right-sided radiotherapy (<0.1 percent).
“Estimated lifetime risks of major coronary events for patients who receive radiotherapy for breast cancer are now in the range from 0.05 to 3.5 percent, with a typical value of 0.3 percent for a typical scenario,” the authors write.