Radiation is often used to treat breast cancer, but the results of a new study show that the treatment may pose a small increased heart disease risk to patients. Researchers found that radiation given to women on the left could result in a higher risk of developing narrowing of the arteries that lead to the heart. The researchers caution that the overall risk is small but encourage physicians to be aware of the risk when administering radiation.
Radiation therapy uses high-energy rays to stop cancer cells from growing and dividing. Radiation therapy is often used to destroy any remaining breast cancer cells in the breast, chest wall, or underarm area after surgery. A common course of external beam radiation therapy for breast cancer is about six weeks. Researchers have been investigating whether a shorter duration, higher dose of radiation may be as effective as the conventional six to seven week regimen. Recent research suggests that limiting radiation therapy to four weeks at a higher dose may be as effective as the traditional regimen and could reduce side effects.
In the current study, Swedish researchers found that of the 8,190 women diagnosed with breast cancer between 1970 and 2003, 199 of the women had to receive a coronary angiography to be treated for blocked arteries. In an editorial published along with the study, Dr. Timothy Zagar and Dr. Lawrence B. Marks of the University of North Carolina at Chapel Hill stated that it is unclear how radiation causes damage to the arteries but it is likely that the radiation can damage the cells lining the arteries, which can lead to inflammation, which can then lead to hardening of the arteries.
Dr. Zagar cautioned that the study was conducted over a long period of time and would likely yield different results if today’s methods of delivering radiation were studied. He did not think the study results warranted a change in treatment for breast cancer patients. However, the study may provide physicians additional information to consider when developing treatment options for patients.
- The study, “Distribution of Coronary Artery Stenosis After Radiation for Breast Cancer,” was published in the December 27, 2011 online edition of the Journal of Clinical Oncology, http://jco.ascopubs.org/
- An accompanying editorial entitled, Breast Cancer Radiotherapy and Coronary Artery Stenosis: Location, Location, Location,” was published in the same edition of the Journal.
