Breast cancer radiation may raise heart risk

Women treated with radiation for breast cancer are more likely to develop heart problems later, even with the lower doses used today, troubling new research suggests. The risk, from any amount of radiation, starts five years after treatment and lasts for decades, doctors found.

Patients shouldn't panic, doctors say: radiation has improved cancer survival, and that's the top priority. Chances of a radiation-induced heart problem are fairly small. For example, 4 to 5 of every 100 women who are 50 years old and free of heart risks will develop a major cardiac problem by age 80. Radiation treatment would add one more case, the research suggests.

Women can cut their risk by controlling weight, cholesterol and blood pressure.

Still, the study reveals that the potential harm from radiation runs deeper than many medical experts may have realized, especially for women who already have cardiac risk factors such as diabetes.

And it comes amid greater awareness of overtreatment -- that many women are being treated for cancers that would never prove fatal, leading to trouble down the road such as heart disease.

Some chemotherapy drugs are known to harm the heart muscle, but the new study shows radiation can hurt arteries, making them prone to harden and clog and cause a heart attack. Those who get both treatments have both types of risk.

Artery-related problems the study tracked may be just the most visible of many risks because radiation also can cause valve, rhythm and other heart troubles, said Dr. Javid Moslehi of the Dana-Farber Cancer Institute in Boston.

Like cancer, heart disease develops after "a number of strikes that go against you," such as high cholesterol, he said. "The radiation is just another hit," he wrote in an editorial that appears with the study in today's New England Journal of Medicine.