Most people who have radiotherapy do not develop heart problems following treatment. Radiotherapy treatments will only affect the heart if the heart is in the area that’s treated. This may include radiotherapy given to the chest to treat left-sided breast cancer. However, this is only likely to be a significant problem if the treatment was given over 10 years ago. Today, advances in treatment mean that radiotherapy for breast cancer is unlikely to cause significant heart problems.

Radiotherapy can affect the heart in different ways. It can:

  • change the inside of the blood vessels that supply the heart, making it easier for fatty deposits to collect causing the arteries to narrow
  • damage the heart muscle so that it doesn’t work as well
  • damage the heart valves.

We have more information about heart disease.

The effect of radiotherapy on the heart may not be seen for 10 or more years after treatment.

If you’ve had radiotherapy and the area treated included your heart, make sure you lead a healthy lifestyle to avoid any further damage to your heart. It’s sensible to have regular blood pressure and blood cholesterol measurements taken. You may also need to have an ultrasound of your heart (echocardiogram) carried out from time to time. Your GP can arrange these tests for you. If you notice any symptoms of heart disease, tell your cancer doctor or GP as soon as possible.

Working together to create information for you

We worked with British Heart Foundation to write our content on heart health.

Thank you to all of the people affected by cancer who reviewed what you're reading and have helped our information to develop.

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Back to Cancer treatment and your heart


A few chemotherapy drugs affect the heart. Your hospital team will talk to you about any risks of the drugs you’re having.

Hormonal therapies

Treatment with hormonal therapies can sometimes increase the risk of heart problems.

Surgery for cancer

You’ll usually have tests to check your heart before you have an operation to treat a cancer.

Cancer research trials

If you take part in a clinical trial, you will have regular checks for any side effects.

Managing heart problems

If you have heart problems during cancer treatment, your doctors will help you decide on the best way to manage them.