For many women with breast cancer, radiation is an integral part of their treatment plans. But a landmark study, entitled Risk of Ischemic Heart Disease in Women after Radiotherapy, (Darby, et. al., published in the New England Journal of Medicine, 2013), has identified a troubling side effect of large radiation doses near the heart.
For many women with breast cancer, radiation is an integral part of their treatment plans.
But a landmark study, entitled Risk of Ischemic Heart Disease in Women after Radiotherapy, (Darby, et. al., published in the New England Journal of Medicine, 2013), has identified a troubling side effect of large radiation doses near the heart. The research findings identify that for every Gray (a unit of radiation dose measurement), a woman’s chance of a major coronary event goes up by 7.4 percent. As the report cited, “Randomized trials have shown that radiotherapy for early-stage breast cancer can reduce the rates of recurrence and of death from breast cancer. However, long-term follow-up in some trials has shown that radiotherapy can also increase the risk of heart disease, presumably through incidental irradiation of the heart.” These results were reproduced and confirmed by another key study published in 2017 (van den Bogaard et al.) in the Journal of Clinical Oncology in which patients were treated with modern radiation techniques and thus applicable to the patients of today.
The effect was more pronounced in breast cancers of the left breast, which is closer to the heart, and in women with pre-existing heart disease. The average participant in the study had a mean dose of 4.9 Grays; any exposure increased the possibility of heart disease events.
Given this information, the lower the radiation exposure to the heart, the lower the risk of developing heart disease. There are several techniques used by radiation oncologists to decrease the dose to the heart. Proton therapy is one such modality that can often significantly reduce heart dose by allowing us to control where the radiation beam stops.
“With conventional radiation and X-rays, the radiation enters the body but it also exits, and it deposits radiation dose as it exits the body,” said Dr. Christine Fang, radiation oncologist at Seattle Cancer Care Alliance, Proton Therapy Center. “With proton therapy, there is no exit dose.”
“There’s no extraneous dose to areas that don’t need radiation,” Dr. Fang said.
So, what can breast cancer patients do to advocate for themselves and their health?
First, review your radiation plan with your physician. Given your case and health history, what is the lowest possible therapeutic radiation dose?
Secondly, investigate targeted radiation modalities such as proton therapy. Radiation technologies that stop at the tumor and spare nearby organs from excess radiation can reduce the overall impact to the heart.
And finally, ask your doctor to evaluate your risk of radiation-related heart disease, and weigh it against the risk of recurrence. This will help you make the best decision for your long-term health.
This study will help breast cancer patients evaluate risks and choose their treatment plans.
The Fred Hutch Proton Therapy Center currently has a clinical study open aimed to determine whether proton therapy leads to lower risk of long-term side effects. Most patients that have involvement of the lymph nodes will be eligible for this study.
