Heart Risks of Cancer Therapy
Understanding the Heart Risks of Cancer Therapy
The Heart: While worrying about cell counts and treatment schedules, it can be challenging to consider the long-term implications of a childhood cancer diagnosis. Survival is the number one priority.
However, certain common treatments for cancer carry risks for later in life. By being aware of how and when these effects may appear, you and your child’s care team will work together to monitor for adverse reactions even after cancer treatment is complete.
This article specifically discusses certain cardiac (heart) risks from cancer treatment.
Weighing Risk is Built In to Prescribing Cancer Therapy
Medical training teaches providers to weigh the benefits versus the risks of a particular course before recommending it. They are required to discuss these risks with you before you consent to treatment, outlining the suggested steps, based on expert guidance, to minimize the likelihood of future negative outcomes.
This process helps to ensure that doctors do not subject your child to a regimen that will be more harmful than helpful. If you feel confused or unsure, do not hesitate to ask your provider for more details.
No cancer treatment is without risk, but if a treatment’s long-term risks are not considered “worth it” for their immediate benefit, the care team will not offer the therapy. This is a decision you and the care team should make together.
Types of Treatments and Their Potential Heart Risks
Anthracycline Chemotherapy
Anthracyclines are a type of antibiotic made from Streptomyces bacteria. Unlike most antibiotics, which are used to treat infection, doctors give anthracyclines to help stop the spread of certain cancers. They do this by disrupting the cancer cells’ DNA.
Anthracyclines are some of the most powerful chemotherapy drugs available. However, they also carry a higher risk of cardiotoxicity (toxic to the heart) than other drugs. This is because they can damage healthy body cells while targeting cancer cells.
A person’s body can easily replace damaged cells from particular organs, like the skin or intestines. Unfortunately, the cells of the heart muscle are very difficult for the body to repair.
Heart Failure
As a person ages, this cell damage can cause the muscular walls of the heart to become thin and floppy. Such changes make them unable to effectively pump blood out of the heart and around the body. This condition is called cardiomyopathy, and it eventually leads to Congestive Heart Failure (CHF). In CHF, the heart’s failure to properly pump blood causes fluid to build up in the body. This fluid build-up leads to symptoms such as shortness of breath, swelling, fatigue, dizziness, and poor appetite. If not treated, CHF can lead to death.
Heart Valve Damage
Patients treated with Anthracycline chemotherapy are also at risk of heart valve disease. In this condition, the valves between the heart’s chambers or between the heart and major blood vessels become stiff or start to break down. Over time, this results in limited blood flow through the valves or valve regurgitation (blood flowing backwards through the valve). This abnormal blood flow leads to symptoms of CHF.
Abnormal Heart Rhythm
A third risk of Anthracycline treatment is abnormal heart rhythms (cardiac arrhythmias). Anthracycline can irritate the electrical cells of the heart. This irritation results in episodes where the heart beats too slowly, too quickly, or in a chaotic manner. All of these abnormal rhythms lead to decreased heart-pumping function. They also increase the risk of blood clots.
Factors that Affect Anthracycline Risk
Anthracycline toxicity risks increase at higher doses and when the drug is delivered more rapidly. The chemo dose, treatment length, and pace of therapy depend on the type and stage of cancer being targeted. Your provider may also choose to change the dose or pattern of chemo over time. They will make these decisions based on response to treatment and tolerance of side effects.
The patient’s age at the time of Anthracycline treatment is also an important variable for the risk of future complications. Generally, the younger a child is at the start of anthracycline therapy, the higher the risk.
Radiation Therapy
Radiation, or radiotherapy, is another vital tool in treating cancer. It can either be used by itself or in combination with chemotherapy, depending on the type and location of cancer. In radiation, technicians direct beams of intense energy toward areas of the body where cancer is growing. These beams kill cancer cells, either shrinking the tumor or preventing it from growing larger.
The risks of radiation include many of the same ones associated with chemotherapy. It may cause cardiomyopathy, heart failure, valve disease, or abnormal heart rhythms.
Pericarditis
Radiation may also result in inflammation or scarring of the pericardium. The pericardium is the fluid-filled sac surrounding the heart muscle.
Pericardial inflammation, called Pericarditis, usually occurs within a short period (days to months) after receiving radiation. Symptoms such as fever, tachycardia, and sharp chest pain made worse by taking deep breaths or lying down may signal pericarditis. The doctor may also hear a scratching sound when listening to the heart with a stethoscope. This sound is called a pericardial friction rub.
Pericardial Fibrosis
Scarring of the pericardium, called fibrosis, is usually a late-term problem of radiation. It often appears years after treatment. The scars cause the pericardium to become stiff, which restricts the ability of the heart muscle to squeeze and relax effectively. This impairment leads to symptoms such as fatigue, dizziness, and shortness of breath.
Coronary Artery Disease
In addition, radiation sometimes causes coronary artery disease (CAD). In CAD, the arteries supplying blood to the heart muscle become narrow and prone to blockage or spasm. These changes can ultimately lead to high blood pressure or a heart attack and generally appear years after treatment.
Factors that Affect Radiation Risk
Cardiac radiotherapy complications are more common when the area treated includes the chest, spine, or abdomen. Heart problems are more likely to occur at higher radiation doses (more intense energy). The use of radiation in combination with other treatments also increases the risk of heart troubles.
Corticosteroids
Corticosteroids (such as prednisone and dexamethasone) are a type of hormone used for multiple purposes during cancer treatment. First, corticosteroids attack the cancer itself. Second, they are helpful in managing side effects such as inflammation and immune system dysfunction.
However, corticosteroids can lead to high blood sugar levels, elevated blood pressure, abnormal weight gain, and poor sleep. All of these side effects increase a patient’s risk for CAD, diabetes, and stroke.
Fortunately, your child’s care team can usually manage the side effects of corticosteroids easily with careful monitoring and treatment.
Thinking Beyond Cancer Treatment
The development of chemotherapy, radiation, and corticosteroids has led to a drastic improvement in survival rates for childhood cancer. Even so, awareness of their possible side effects is essential.
Diagnostic tests may detect abnormalities before symptoms manifest. Additionally, long-term follow-up is key to staying on top of potential negative effects from cancer treatment. Your child’s care team will work with you to create a plan for long-term follow-up.
In a follow-up article, we will dive deeper into the specific expert recommendations for long-term follow-up to monitor for cardiotoxicity.
References
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