Every patient who’s being treated for cancer should talk to their oncologist about the risk of heart-related complications. We’ve learned a lot in recent years about which cancer treatments can affect the heart and who is most at risk.
Some people are at more risk than others. People who have had heart conditions such as heart failure and cardiomyopathy in the past may have a weakened heart that’s more vulnerable to damage from some forms of cancer treatment. High blood pressure, also known as hypertension, is emerging as a major risk factor for heart-related complications of cancer treatment, especially for those already more susceptible to developing high blood pressure, such as African-Americans and older adults. However, whether you have these risk factors or not, we have to think about the type of treatment you need and whether it’s cardiotoxic, or damaging to the heart.
What cancer treatments affect the heart–and how?
Only a few groups of cancer medications have a direct effect on the heart: anthracyclines, radiation therapy and targeted therapies for HER2-positive breast cancer.
Anthracyclines
Anthracyclines have been used successfully since the 1970s to treat breast cancer, lymphomas (cancers of the lymphatic system) and sarcomas (cancers of the bones, muscles and the body’s connective tissues). The most commonly used medication from this group is a chemotherapy drug called doxorubicin. In recent years, we’ve learned that the dosage of anthracyclines is related to their effects on the heart, and there have been changes in cancer treatment plans to limit these effects.
Radiation therapy
A history of radiation therapy also can affect the heart’s function. Radiation oncologists have done a tremendous amount to minimize the damage radiation can have on the heart, but I do have some patients who have been exposed to radiation in the past and are seeing me for heart valve disease or coronary artery disease. These known effects of radiation therapy can appear years after cancer treatment ends.
Targeted therapies for HER2-positive breast cancer
These medications treat breast cancer that has tested positive for higher-than-normal levels of a protein called HER2, or human epidermal growth factor receptor. The drugs trastuzumab and pertuzumab, which often are given alongside chemotherapy, are the main culprits in this group. However, the heart-related effects of these drugs aren’t related to their dosage, so we have to watch patients closely when they’re on HER2-targeted treatment.
Related research: How we identify and treat heart risk during potentially cardiotoxic therapy
Indirect effects of cancer treatment
New combination therapies, as well as targeted therapies, can have unexpected side effects, and there are no set guidelines on when cardiologists need to check the hearts of patients who have received or are receiving them.
We’re starting to see a small percentage of patients receiving cancer treatment who have a drop in the amount of blood pumped out of the heart with each heartbeat (ejection fraction). That can be a symptom of heart failure. Some patients on newer therapies have developed myocarditis, which is an inflammation of the heart muscle that can be fatal. Immune checkpoint inhibitors, which boost the immune system’s ability to fight cancer, are one example of cancer treatments that have been linked to cases of myocarditis. Patients who are receiving therapies targeting tumor pathways (such as vascular endothelial growth factor (VEGF) inhibitors) may develop high blood pressure as a consequence of treatment that may put them at risk for heart failure and stroke. Elevation of blood pressure can be successfully treated.
How to reduce heart risks during cancer care
First and foremost, it’s critical to let your oncologist know if you’ve had heart problems in the past. Your doctor also should know if you have high blood pressure or diabetes, because these conditions can increase your risk for a heart problem even before starting cancer treatment.
When your oncologist recommends therapies, ask how they could potentially affect your heart. If the oncologist says the treatment could affect your heart, or if it’s not known whether it could, it’s a good idea to meet with a cardio-oncologist like me. My colleagues and I are cardiologists who have expertise in how cancer treatments interact with the heart.
If possible, you should have an echocardiogram before cancer treatment begins. This gives the oncologist a baseline reading of your heart, so they can better detect any changes that may happen during treatment. For example, if your oncologist notices a drop in your ejection fraction, we can prescribe diuretics or other medication to help the heart pump more effectively. If increases in your blood pressure are seen during therapy, you should be prescribed medications and your blood pressures should be followed to make sure that control is adequate.
Both oncologists and cardiologists need to keep up to speed on the latest treatments and research. I was part of a Feb. 2018 publication by the American Heart Association that highlighted the important intersection between breast cancer and heart disease. In December 2017, the Food and Drug Administration (FDA) organized a workshop on cardiotoxicity of cancer treatments and on the heart effects of immune checkpoint inhibitors and in February 2018 the American College of Cardiology hosted the Heart House Roundtable on Cardiovascular function and Cancer treatment that I had the privilege to chair. These workshops bring together doctors, patient representatives, representatives of the pharmaceutical industry and regulators, all of whom wanted to make sure everyone has the latest information to keep patients safe during cancer treatment. In addition to workshops, there is growing need for education of cardiologists and oncologists in this area and professional societies, such as the American College of Cardiology are very important. In February 2018, the ACC hosted its second live course here in Washington on cardiovascular care for the oncology patient that was attended by more than 300 hundred health care professionals.
The ACC Cardio-oncology section has created two important resources for education of physicians and patients in this field that I recommend highly to my patients and colleagues:
With what we’ve learned and continue to learn about the potential heart-related risks of cancer treatment, oncologists and cardiologists alike are more prepared than ever to address these problems before they get out of control. By understanding the risk, planning for it ahead of time and calling in a cardiologist if needed, we can make the difference between a minor issue that needs to be monitored and a major problem with consequences that last for years to come.
