A woman with a left breast cancer is at risk of damage to her heart from unnecessary radiation. The heart is located on the left side of the chest, immediately behind the rib cage. Your radiation oncologist typically has to use special techniques to protect your heart and it’s important you know what questions to ask.

In 2013, Dr. Darby and colleagues published a study in the New England Journal of Medicine (NEJM)which quantified the risk associated with radiation to the heart.

While radiation oncologists have tried to reduce dose to the heart for many years, this study was really the first to show what the actual risks were. Radiation is measured in “Gray” and typically we prescribed 40-50 Gray to the breast or chest wall (after mastectomy) to eradicate microscopic breast cancer cells.

The NEJM study stated:
Rates of major coronary events increased linearly with the mean dose to the heart by 7.4% per gray (P<0.001), with no apparent threshold.

The Mean Heart Doses typically delivered were:

  • 6.6 Gy left breast
  • 2.9 Gy right breast
  • 4.9 Gy overall (range, 0.03 to 27.72)

Multiply these numbers by 7.4% and the risk of a cardiac event is 20 -49% for women with left sided breast cancer receiving radiation!

Dr. Darby’s study gained a lot of attention and fortunately, radiation oncologists began utilizing different techniques to spare the heart.

In my practice, I offer the following techniques:

Accelerated Partial Breast Irradiation using the SAVI catheter.

This technique is an option for women with small tumors (<3cm), clear surgical margins and negative lymph nodes. Only the surgical cavity (where the tumor was removed) is treated so no radiation is delivered to the remaining breast tissue, nor the heart or lung. Prone Breast.
For women who need the entire breast treated, they can be treated with radiation lying face down.

Deep Inspiratory Breath Hold (DIBH)
Women with more advanced left breast cancer will need radiation to the whole breast (or chest wall after a mastectomy) along with the lymph nodes under the arm (axilla), above the collarbone (supraclavicular lymph nodes) and possibly even the internal mammary lymph nodes along the sternum. More information about DIBH can be found here.

If I am still concerned that a woman’s heart is receiving too much radiation, I will recommend proton therapy.


Patient-focused treatment, and an individualized approach to oncology means Dr. Norleena Gullett is not just treating cancer, she's treating the whole person.