Cancer Therapy and your Heart

“First do no harm” gains special meaning in the treatment of cancer. Regardless of whether treatments are physical (such as radiation therapy), chemical (such as chemotherapy) or biological (as in the case of biologic modifiers) – they can all cause harm.

Oncologists and Cardiologists often work together to balance the goals of the oncologist, whose aim is to kill cancer cells, against the goals of the cardiologist, whose aim it is to protect the heart against the harm of the cancer treatment. The concept of the cardiologist and the oncologist working together was already a reality in the 1980’s and can be termed onco-cardiology.

WHY?

As you can see in the first picture, a cell that mutates, or changes from normal cells, usually doesn’t last very long but, as can be seen in the second picture, cancer cells lose their normal growth and become out-of-control, rapidly-dividing cells.

Chemotherapy targets any rapidly dividing cells, the problem is that it does not know the difference between rapidly dividing cancer cells and rapidly dividing healthy cells that are found in the hair follicles, bone marrow and gastro-intestinal tract.

Because of this cancer treatment can cause:

• Hair loss

• Bone Marrow Depression with: low white cell counts (increased susceptibility to infections), low platelets (increased bleeding), low red blood cells (causing anaemia and tiredness).

• Effects on the gastro-intestinal tract can cause inflammation of the gums in the mouth (glossitis).

The improvement in breast cancer survival is directly related to earlier detection (through screening and self examinations) and improved treatment.

Elimination of the disease has evolved over time, first with the use of combined treatments (chemotherapy and radiotherapy), with improved chemotherapy drugs such as the anthracyclines (adriamycin) and taxanes (paclitaxil) and more recently with the introduction of trastuzumab (herceptin) and similar drugs for those who are HER2 positive.

Cancer treatments can also be cardiotoxic i.e. cause damage to the heart. Chemotherapy can directly kill or cause abnormal functioning of heart cells. Radiotherapy can damage the endothelium (the lining of the cells of the blood vessels) and so cause problems with blood supply to the heart, associated with coronary disease. The incidence of cardiotoxicity is of particular concern in people being treated for breast cancer because of the use of chemotherapy and radiotherapy.

In addition to preventing and treating the cardiotoxicity it remains imperative for the medical fraternity to now discover ways to further decrease the toxic effects of our therapies.

Cardiotoxicity can result in heart failure and damage to the vessels may result in heart attacks and, sometimes, clots in the lungs. Abnormal heart rhythms may also (rarely) occur.

The most common effect of chemotherapy on the heart is the development of a cardiomyopathy. This is a disease of the heart muscle resulting in abnormal heart function and, ultimately, heart failure.

Some people may be at increased risk of developing heart problems during their cancer treatment. This generally includes individuals who are young, elderly, have high blood pressure and those people receiving chemotherapy who have previously received radiotherapy.

Prior to starting cancer treatment it is a very good idea to obtain an assessment of your heart. This requires an appointment with a cardiologist at which time an examination, electrocardiogram (ECG) and echocardiogram will be performed.

An echocardiogram is an ultrasound (sonar) of the heart during which the function of the heart is measured.

A radio-isotope study (called a MUGGA study) can also be used to assess your heart function.

By visiting a cardiologist, abnormality of heart function can be detected in the early stages of the cardiomyopathy at which time early treatment can be initiated and preventive measures taken to prevent further deterioration.

Abnormality of heart function that goes untreated can progress to heart failure where the heart is unable to function adequately and unable to supply enough blood to meet the body’s needs. Symptoms of heart failure include shortness of breath, fatigue and ankle swelling.

All patients should have their heart assessed before starting chemotherapy or radiotherapy and monitor their hearts during their cancer treatment.

By visiting a cardiologist and obtaining an assessment before you start your treatment it provides your cardiologist with a “base line”. As your treatment progresses the cardiologist can compare later assessments to your base line and determine how much damage is being done to your heart

If you are already having treatment, or even if you have completed your treatment, it is never to late to visit the cardiologist for an assessment, especially if you are experiencing shortness of breath, fatigue or swelling of the ankles.

Written by Dr Len Steingo

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