Heart problems and breast cancer treatment

Some breast cancer treatments and therapies can cause heart problems. These may be short-term or can continue after you finish treatment.

Your medical oncologist will talk to you about the possible effects of the treatment they recommend. They may organise tests and ongoing monitoring or send you to a specialist.

Cardio-oncologists specialise in how cancer treatment affects heart function and they can assess you before treatment starts.

Signs of heart problems

Many things can cause heart problems. It is important to find the right reason so you can have the right treatment. Your doctor may test your heart before treatment as well as several times during treatment.

Most heart problems resolve once treatment finishes.

Symptoms of heart problems may include:

• fast or irregular heartbeat
• breathing problems such as shortness of breath and coughing
• swelling of the feet and lower legs
• feeling weak, dizzy and tired.

What increases your risk

The risk of developing heart problems can increase depending on:

• your age
• any heart issues you may already have
• whether you are overweight
• if you smoke.

Chemotherapy and heart function

The anthracycline group of chemotherapy drugs (doxorubicin and epirubicin) can affect the way the muscle in your heart works. This is one of the rarer side effects of chemotherapy.

If you have an existing heart condition, these drugs may not be suitable for you.

Before you start treatment with these drugs, your specialist needs to make sure your heart is working normally. They may arrange tests to check your heart function, such as an echocardiogram.

During treatment, your team will monitor you carefully to reduce any risk of heart problems occurring.

Sometimes your specialist may refer you to a cardiologist. This is likely if you have other medical conditions that increase your risk of developing heart problems from chemotherapy.

People who are at a higher risk sometimes have a lower dose of the chemotherapy.

Radiation and heart problems

Damage to the heart from radiation is rare.

Technology has improved so that radiation oncologists can minimise the dose of radiotherapy to the heart. Some hospitals offer a technique is called deep inspiration breath hold (DIBH) radiotherapy as a way to reduce radiation.

HER2 therapy-related heart problems

Some HER2 therapies, such as trastuzumab, can occasionally weaken the heart muscle. For this reason, your heart function will be checked regularly when you are on these treatments.

You will usually have a heart test before you start HER2 treatment. Every 3 months the test will be repeated to check for any changes.

Once your test results have been stable for more than a year, your medical oncologist may reduce how often you need the tests. They will talk to you about this.

Hormone-blocking therapies and targeted therapies

Some hormone-blocking therapies (aromatase inhibitors) can increase cholesterol levels. Higher cholesterol increases the risk of heart problems such as coronary artery disease.

Tamoxifen can increase the risk of blood clots developing. If you have a history of blood clots, your specialist may:

• prescribe a medication to prevent problems, such as a blood thinner
• prescribe a different hormone-blocking medication.

Ways to test the heart function

There are 2 ways to check the heart function. Your medical oncologist will talk to you about which they recommend for you, and why.

Echocardiogram: this is an ultrasound of the heart. It is usually done in the cardiology department.

Gated Blood Pool Scan: this is a nuclear medicine scan and is done in the radiology department. You need an injection of contrast.