A study showed that women with cancer in the left breast treated with radiation therapy were much more likely to have cardiac stress test abnormalities years later than women who received radiation therapy on their right breast. At an average of 12 years after radiation therapy, 59% of women with left-sided breast cancer had stress test abnormalities compared to only 8% of women with right-sided breast cancer. All of the women in this study were treated with radiation therapy after lumpectomy for early breast cancer.
Because the heart is on the left side of the chest, it's likely the heart unintentionally was exposed to more radiation in women who received radiation therapy for cancer in the left breast. Exposing the heart and coronary arteries to radiation may cause damage to the heart and probably explains the stress test abnormalities the researchers found.
It's important to note that this study looked at women who got radiation therapy between 1977 and 1995. Today, advances in technology are making the heart and surrounding breast tissue increasingly less likely to be exposed to radiation. Computers now are used to plan radiation treatment that is extremely precise. The computer aims just the right amount of radiation only at tissue that needs to be treated. Other new technology gives your radiation oncologist a wider and safer choice of radiation energy sources. Together, these two advances give your radiation oncologist the ability to avoid unnecessarily exposing your heart to radiation intended for the breast area. Some radiation therapy equipment actually tracks heart beats and the movement of your lungs and effectively blocks those tissues from any radiation exposure.
If radiation therapy is part of your treatment plan, 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 therapy required to effectively treat the breast cancer. If you've received radiation therapy in the past, it's important that your doctor is familiar with your medical history and understands any treatment-related risks you may have. Together, you and your doctor can plan how best to monitor and screen for any complications that may happen.