The heart needs extra protection from radiation during breast cancer treatment.
When a patient holds her breath, it changes the position of her heart.
An innovative device assists in precise delivery of radiation, away from the heart, while the patient is holding her breath.
Radiation is an important and effective tool when it comes to treating breast cancer. But in the past, it’s had unfortunate side effects on the heart.
Published data shows that because the heart is so close to the left breast and chest wall, patients whose hearts were exposed to radiation had significantly increased risk of major cardiac problems such as heart disease or heart attack. The risk was especially high for patients with preexisting heart conditions. “That is why we go all-out in protecting the heart during the course of radiation therapy,” says Astrid Morris, MD, a breast cancer radiation oncologist at the Swedish Cancer Institute (SCI) in Seattle. “We have made side effects on the heart from radiation a historical footnote.”
That’s because SCI uses the cutting-edge Active Breathing Coordinator™. This advanced system takes advantage of the anatomical change in the placement of the heart when a patient holds her breath in order to safely deliver radiation.
“The left ventricle is very close to the left breast and chest wall, and on the surface of the ventricle runs the left anterior descending coronary artery,” Dr. Morris says. “If this artery is harmed, it’s the most common culprit for any type of heart attack or ischemic heart disease so protecting this area is crucial. When you hold your breath, the heart gets pulled down and back by the diaphragm. We take advantage of this temporary change of heart location and only use radiation during that deep breath hold.”
Further protection is offered by a multileaf collimator, a device which blocks radiation. Because every patient’s anatomy is different, this requires an individualized approach to treatment. Dr. Morris and her team use a computerized plan to determine how to use the Active Breathing Coordinator and the multileaf collimator to best advantage in each case.
Patient education is also an important part of treatment prep. Dr. Morris shows patients pictures so they understand how the process works and that “it is truly friendly equipment,” she says. At home, patients practice holding their breath comfortably for about 20 to 30 seconds to get used to what the treatment requires.
Patients not only have to hold their breath for a prolonged period of time, but they also have to hold the same volume of breath each time. That’s where the Active Breathing Coordinator comes in, thanks to a spirometer that measures the volume of air a patient inhales. During planning sessions, Dr. Morris calculates the ideal air volume — about 2/3 of a patient’s deepest inhale — to use as a benchmark during the treatment. Doctors also take scans of the patient’s heart while she is holding her breath and breathing regularly so they can see the position of the heart at both times.
“Radiation delivery should be within 1 millimeter of precision every time we treat, so we want it to be reproducible and exactly the same every time we turn that beam on,” Dr. Morris says. “The Active Breathing Coordinator allows us to do that."
The radiation beam is only turned on once the heart is safely away from the targeted treatment area during those 20- to 30-second breath holds.
That means patients usually have to hold their breath several times during the course of one treatment session to allow for delivery of the full daily radiation dose.
SCI has been at the forefront of this technology, using the Active Breathing Coordinator for more than 10 years. “We worked with the developers of this program and therefore had a chance very early on to work on solidifying this technique,” says Dr. Morris, adding that SCI is a teaching site for use of the Active Breathing Coordinator.
Dr. Morris says the goal is to have well-informed patients who are active partners in this treatment process. “Because everyone is concerned about their heart and wants to reduce their risk of heart disease, there is committed buy-in and a positive attitude among Swedish patients,” she says. “Instead of being fearful or uncertain, patients have the understanding that we have techniques that won’t put them at risk for heart disease.”