Cancer treatment and the heart: chemotherapy cardiotoxicity explained

Cardiotoxicity simply means harm to the heart from a treatment. The British Heart Foundation lists some cancer treatments, such as chemotherapy, among the possible causes of heart failure, and Macmillan explains that some cancer treatments can affect how the heart works. This may cause heart problems that are temporary or permanent.

It is important to keep this in proportion. Macmillan says the risk depends on the type of treatment and how much you have, and for radiotherapy it says most people do not develop heart problems. Cancer teams weigh the benefit of treating the cancer against any heart risk, and the aim is to plan treatment so that the risk is as low as possible.

Macmillan describes different treatments in turn. The table summarises what it says about each, and it notes that for information on a specific drug you can ask your cancer team or pharmacist, or check the electronic Medicines Compendium.

Macmillan says different heart conditions cause different symptoms and that some can be similar to those of other conditions, so your cancer team will explain what to look out for. The NHS lists the symptoms of heart failure as breathlessness during everyday activities or lying down, feeling weak, light-headed or very tired, swelling of the feet, ankles, legs or tummy, sudden weight gain, coughing at night and coughing up frothy pink phlegm.

Macmillan describes the usual signs of a heart attack as sudden chest pain or discomfort that does not go away, possibly spreading to the arms, neck, jaw, stomach or back, with sweating, dizziness, breathlessness or feeling sick. It says to phone 999 for an ambulance straight away. The NHS advises urgent GP advice or NHS 111 for breathlessness lying down, frothy pink phlegm or sudden weight gain, and 999 for severe difficulty breathing, blue, grey or pale lips or skin, or someone who has passed out and is not responding normally. If you are in treatment, tell your cancer team promptly about new symptoms, since your care plan may need to change.

Macmillan explains that before treatment your cancer doctor may check your heart health, asking whether you have heart problems or risk factors such as high blood pressure, high cholesterol or diabetes, and what treatment you take for them. They may speak to your GP or cardiologist. If you already have a heart condition this may affect which cancer treatment is chosen and how it is planned, so it is important to tell them about any heart problems.

You may also have heart tests, even if you do not have a heart problem, for some treatments, and these can be repeated during and after treatment. Macmillan also suggests healthy lifestyle changes before treatment as a way to improve long-term heart health. Blood pressure and cholesterol checks, and scans to see how the heart is working, may form part of follow-up.

Macmillan says that if you develop heart problems during or after cancer treatment, your cancer doctor will talk to you about managing them. Your treatment may be changed: stopping for a time, lowering the dose, switching to a drug that is less likely to cause heart problems, or stopping completely. Your cancer doctor may arrange for you to see a heart specialist (cardiologist), and some heart problems may be managed and monitored by your GP.

Heart failure and related conditions are treated like heart failure from other causes, with medicines, lifestyle measures and sometimes devices. The NHS describes treatments for heart failure including diuretics, medicines that widen blood vessels and beta blockers, as well as cardiac rehabilitation, and the British Heart Foundation lists heart failure medicines among options to protect and improve heart function.

Some heart problems appear months or many years after treatment. Macmillan says that if you had cancer treatment as a child you may have a higher risk of developing heart problems as an adult, depending on the treatment. Follow-up appointments may be with a GP, practice nurse or hospital cardiology team and may include blood tests, blood pressure checks and heart scans. Macmillan says they are particularly useful for people who developed a heart problem during or after treatment, who had treatment that may cause problems many years later, or who have other risk factors.

If your treatment is unlikely to cause heart problems you may not need follow-up, but Macmillan says that if you have other risk factors you can talk to your GP or nurse about your risk and a health check. It also advises asking your doctor about pregnancy after cancer treatment, because pregnancy puts pressure on the heart.

Macmillan says you can improve your heart health at any age, even with a heart problem. Its tips include a healthy diet, limiting alcohol (binge drinking can increase the risk of arrhythmias and high blood pressure and can damage the heart muscle), keeping to a healthy weight, staying active, stopping smoking and managing stress. The British Heart Foundation recommends keeping alcohol below 14 units a week for people with heart failure.

On the NHS, heart checks around cancer treatment are organised by your oncology or haematology team, with cardiology referral when needed. If you have your cancer treatment privately, the same principles apply, and it is important that your oncologist, GP and any cardiologist share results so that treatment decisions are made on the full picture. Ask who will monitor your heart and how often.