When Curing Cancer Hurts Your Heart

Combining Knowledge from Cardiology and Oncology

Looking after the heart in patients with cancer.

As survival rates for cancer patients have increased over the past 25 years, so has the need for long-term follow-up and monitoring of these cancer survivors. This includes looking after their cardiac needs. To meet this challenge, a new field of medicine has arisen that combines the expertise of specialists in both cardiology and oncology.

What Is Cardio-Oncology?

Cardio-oncology refers to a clinical subspecialty that is focused on understanding, managing, and treating the possible cardiac side effects—known as cardiotoxicity—of cancer treatments such as chemotherapy and radiation therapy.

Over the past few years, cardio-oncology clinics have sprung up in major medical centers across the nation to provide integrated and interdisciplinary care to cancer patients with cardiovascular risks. Most cardio-oncologists are cardiologists who have a special interest and often special training in the cardiac effects of cancer treatments.

What Is Cardiotoxicity?

As noted above, cardiotoxicity is a medical term used to refer to damage that occurs to the heart due to a toxin. Such a toxin may be an illegal drug or exposure to a toxic pollutant, or it may come in the form of a medically administered substance, like many of the agents used to treat cancer.

When it comes to the damage posed by chemotherapy, cardiotoxicity is generally divided into five different categories:

  • Direct damage from chemotherapy that causes a decreased ability of the heart to pump properly (a condition known as systolic dysfunction)
  • Cardiac ischemia (decreased blood flow and oxygen supply to the heart)
  • Arrhythmias (abnormal heart rhythms)
  • Pericarditis (inflammation of the pericardium, the lining of the sac in which the heart is enclosed)
  • Other electrocardiographic abnormalities known as repolarization abnormalities, which have to do with the way molecules and minerals such as potassium and calcium are processed by heart cells

    What Cancer Treatments Cause Cardiotoxicity?

    Many of the agents that are used to kill cancer cells are also known to kill healthy cells in the process, but some do so more commonly than others. Experts usually consider chemotherapeutic agents to fall into two types with regard to potential cardiotoxicity: Type 1 agents cause direct damage to the pumping function of the heart that is usually irreversible; and Type 2 agents cause more indirect cardiac dysfunction that is often reversible. The damage caused by Type 1 agents is dose-related, meaning that more cardiac damage is likely to occur at higher medication doses, while the potential damage from Type 2 agents is generally not dose-related.

    Type 1 chemotherapy agents include medications such as doxorubicin, idarubicin, epirubicin, cyclophosphamide and docetaxel. Type 2 agents include trastuzumab, bevacizumab, lapatinib, sunitinib and imatinib.

    Also, radiation therapy that is performed without adequate shielding of the heart can cause coronary artery disease, damage to heart valves, and pericardial disease, all of which may become apparent later.

    In the treatment of certain cancers, such as breast cancer, the issue of cardiotoxicity is particularly important. This is due to the large number of women with breast cancer who have received and will continue to receive combination therapy with both Type 1 and Type 2 agents, such as anthracycline-trastuzumab combination therapy. According to the Mayo Clinic, an average of 17% of patients receiving the anthracycline-trastuzumab combination for the most aggressive forms of breast cancer end up having to stop therapy due to the cardiac complications. However, the cardiotoxicity with this particular combination has been found to be reversible in the majority of patients if the treatment is stopped immediately.

    What Do Cardio-Oncologists Do?

    The role of the cardio-oncologist is to help evaluate cancer patients who may be at particularly high risk for these cardiotoxic side effects, and work with the oncology team to minimize and manage these risks wherever possible.

    The cardio-oncologist will also help monitor patients for subsequent cardiotoxicity. This may involve performing cardiac diagnostic tests, such as echocardiography and cardiac MRI, that evaluate not only the pumping function of the heart but also the function of heart valves as well as the heart’s surrounding structures.

    If you or someone you know must undergo treatment for cancer, you may wish to ask your oncologist about the risks to your heart and what can be done to help mitigate those risks.


    Hong RA, Iimura T, Sumida KN, Eager RM. Cardio-oncology/onco-cardiology. Clin Cardiol 2010;33:733-737.

    Mayo Clinic. For medical professionals: cardio-oncology clinics integrate specialty clinical care. Accessed at http://www.mayoclinic.org/medical-professionals/clinical-updates/cardiovascular/cardio-oncology-clinics-integrate-specialty-clinical-care on October 9, 2014.

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