Harvard Heart Letter

Heart Beat: Radiation for breast cancer linked to narrowed heart arteries

Radiation to treat breast cancer increases the risk of developing narrowed coronary arteries in areas that receive the most radiation, according to a study. Because most of the heart is located in the left side of the chest, the greatest concern is for women who receive radiation to the left breast. Prior studies linked radiation for breast cancer to an increased risk of developing heart disease later.

Swedish researchers evaluated the angiograms of 123 Swedish women who underwent radiation therapy for breast cancer between 1970 and 2003. Those with left-sided breast cancer were about four times more likely than those with right-sided breast cancer to have moderately narrowed coronary arteries, and seven times more likely to have severe narrowing (Journal of Clinical Oncology, published online Dec. 27, 2011).

That may sound scary, but researchers didn't account for other coronary disease risk factors these women might have had. So these findings are not a reason to decline radiation treatment if your doctor thinks it's the best way to fight breast cancer. Equally important, technology has advanced considerably since the time of this study, and doctors are now better able to deliver radiation precisely and protect nontarget tissues. This study suggests that heart arteries should be included as non-target tissue.

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