Imagine the triumph of surviving breast cancer. Every test and procedure, every round of therapy was worth it to save your life. But what is a woman to do if the medication that destroyed her cancer cells had caused another serious health condition: a weakened, damaged heart?
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This is a situation that women with HER2-positive breast cancer used to face when they were treated with targeted therapies. HER2-positive breast cancer has higher-than-normal levels of a protein called HER2 (human epidermal growth factor receptor). Early forms of targeted medications that hunted and destroyed these proteins also unfortunately caused significant heart problems, including weakening of the heart and heart failure.
While defeating cancer is considered a successful therapy, we never want treatment to endanger our patients’ lives. My cardio-oncology colleagues and I are specialized cardiologists who work closely with cancer doctors and patients with HER2-positive breast cancer to give effective cancer care while protecting their hearts as much as we can. In fact, today’s HER2-targeted therapies are now considered one of the safest cancer treatments for these patients. Less than two to three percent of patients will actually develop any symptoms of heart failure while on HER2-targeted therapy for breast cancer.
How we protect the hearts of HER2-positive breast cancer patients
Before treatment begins, we use echocardiograms to measure how a patient’s heart may be affected by their breast cancer therapy. We’re looking at the heart’s ejection fraction, or how much blood leaves the heart with each heartbeat. About 10 to 15 percent of patients with HER2-positive breast cancer have decreased ejection fraction during targeted therapy. That sounds like a lot, but many of those never show any noticeable symptoms, and the changes are often reversible.
Related research: Prevention and Monitoring of Cardiac Dysfunction in Survivors of Adult Cancers: American Society of Clinical Oncology Clinical Practice Guideline
During treatment, we continue to monitor heart function with echocardiograms. Close monitoring gives us an early warning if something is wrong, so we can start patients on medications right away. Beta blockers or diuretics can help improve the heart’s blood-pumping ability and keep their symptoms from becoming more serious. Without this specialized cardio-oncology care, heart damage can lead to patients needing a left-ventricular assist device (LVAD) or even a heart transplant.
Current Food and Drug Administration (FDA) guidelines recommend that patients with abnormal heart function at the start of breast cancer treatment don’t receive HER2-targeted medications. At MedStar we designed an investigator-initiated study that investigates the safety of HER2-targeted medications in patients whose heart shows signs of mildly decreased function (the SAFE-HEaRt trial). We hypothesized that treatment may be safely continued with close observation by cardiologists and initiation of cardiac medications. This clinical study was conducted in collaboration of oncologists at MedStar Washington Hospital Center, MedStar Georgetown University Hospital, and Georgetown Lombardi Comprehensive Cancer Center as well as Memorial Sloan Kettering Cancer Center in New York. The study completed enrollment in December of 2017 and the results will be announced later this year.
Changes in cancer care have led to changes in heart care
We’ve seen massive shifts in the treatment of breast cancer in recent years. People are living longer with breast cancer, even in later stages when the disease has spread. A number of my patients have been on HER2 therapy for 10 to 15 years, and many continue working while they take the medication. In many cases, cancer treatment has become more like treatments for chronic diseases, such as diabetes.
That change in thinking led to cardiologists and cancer doctors partnering to consider the long-term health of the heart for patients with cancer. One such consideration is how much exercise is safe and recommended. When you’re sitting at your desk or watching TV, the heart pumps about three to four liters of blood per minute. But when you’re exercising, it needs to pump six to 10 liters in that same amount of time. If it can’t do that, you may feel short of breath when you exercise. I teach my patients who are on HER2-targeted therapy for their breast cancer to watch for this sign. They know how they should feel when they’re active, so if they notice a sudden shortness of breath during exercise that wasn’t there before, and they can’t explain why, they know it’s time to call me.
Some patients will need to be monitored more closely for their heart function during treatment, and some won’t need as much. I talk daily with my patients’ oncologists and nurse navigators, so we can work together to plan care for each patient’s specific needs.
HER2-targeted therapies are extremely effective in the fight against breast cancer. With what we’ve learned since their introduction, we’ve made sure these medications are safe for patients’ hearts as well. And with good communication among the patient, their oncologist and their cardiologist, we can keep it that way as patients continue their fight against breast cancer for years to come.
