The coronary arteries are large blood vessels that supply the heart with most of the blood it needs to stay healthy. Many factors, including age, inflammation, and high cholesterol, can cause the coronary arteries to narrow or become blocked. Doctors call this narrowing and blockage "stenosis." Stenosis limits blood flow to the heart, which may cause the heart to malfunction or lead to a heart attack.
A large study found women who'd received radiation therapy to treat early-stage breast cancer were more likely to have coronary stenosis compared to women who hadn't received radiation therapy for breast cancer. The women had a coronary angiography, an x-ray test that evaluates the health of the coronary arteries.
The study was done in Sweden, where healthcare is delivered through a national health system. This system allows doctors to track health outcomes and do research on links between health factors and health risks.
All the women in the study had coronary angiography between 1990 and 2004. The 199 women previously treated with radiation therapy for early-stage breast cancer got the radiation between 1970 and 2003.
Besides the higher risk of coronary artery stenosis in women who got radiation therapy for early-stage breast cancer, the researchers also found that:
- Coronary artery stenosis was more likely in women who got radiation therapy for cancer in the left breast compared to women who got radiation for cancer in the right breast.
- The risk of coronary artery stenosis after radiation therapy was lower in women who got radiation therapy delivered in a more focused way ("low risk" regimens, which are more likely to have been done in recent years) compared to women who got less focused radiation ("high risk" regimens, which are more likely to have been done in earlier years).
Experts agree that radiation therapy improves outcomes for many women diagnosed with early-stage breast cancer. Still, other studies have found a link between radiation therapy -- particularly regimens given years ago -- and a higher risk of heart problems. The heart is just below the chest wall. Unintentionally radiating the heart muscle, heart valves, and coronary arteries may damage the heart. Because the heart is on the left side of the chest, the heart may unintentionally be exposed to more radiation in women treated for cancer in the left breast compared to women treated for cancer in the right breast.
Recent advances in radiation therapy technology make it much less likely that the heart (including the coronary arteries) and surrounding breast tissue will be unintentionally exposed to radiation. Doctors today use computers to plan radiation therapy that is extremely precise in its dosing and delivery. The computer aims just the right amount of radiation only at the tissue that needs to be treated. Other new technology gives radiation oncologists wider and safer radiation energy source choices. Some radiation therapy equipment actually tracks heart beats and the movement of the lungs and effectively blocks those tissues from any radiation exposure.
If you've received radiation therapy in the past, it's important that your doctor knows about your medical history and any treatment-related risks you may have. If you've recently been diagnosed with breast cancer and radiation therapy is part of your treatment plan, you may want to ask your doctor about any potential risks for your heart. Understanding all the heart risks associated with radiation therapy is more important for women diagnosed with cancer in the left breast who may be deciding between lumpectomy with radiation therapy and mastectomy without radiation therapy.
If you're going to get radiation therapy to treat breast cancer, it's a good idea to ask your radiation oncologist if the technology being used is up-to-date. Talk to your radiation therapy treatment team about how they'll make sure that you get only the radiation required to effectively treat the breast cancer. Together, you can plan your treatment to minimize any risks.