Effects of breast cancer treatment on the heart and lungs

Rarely, some treatments for breast cancer may increase the risk of developing heart problems and lung problems. These may cause problems many years after treatment ends.

Effects on the heart after breast cancer treatment

Some treatments for breast cancer may increase the risk of developing heart problems. Usually, these problems occur many years after treatment ends. Most people will never experience any effects on the heart. But it may help to understand more about how you can take care of your heart.

The most important risk factor for developing heart problems is pre-existing heart disease, including high blood pressure.

If you are at risk of heart problems, you will be carefully monitored before, during and after treatment. This is to find out if your treatment needs to be changed.


Chemotherapy treatment for early breast cancer usually includes drugs called anthracyclines. Drugs such as epirubicin and doxorubicin are anthracyclines. Research shows that these drugs are good at reducing the risk of breast cancer coming back.

In a small number of people, anthracyclines may cause slight damage to the heart muscle. Because these changes are small, they usually do not cause any symptoms straight away. But they may lead to an increased risk of developing heart problems much later in life.


Radiotherapy to the chest has a very small risk of damaging the heart muscle or the major blood vessels around the heart. This can only happen if you had treatment to the left side. This is because the heart is on the left side of the chest.

Radiotherapy is very carefully planned so that the heart is not in the treated area or only a small part of the heart is in the treated area. This means the risk of developing heart problems is very low.

Hormonal therapy

Hormonal therapy drugs called aromatase inhibitors (AIs) may increase the risk of high cholesterol. This can cause heart problems.

Targeted therapy and immunotherapy

Some targeted therapy drugs, such as trastuzumabtrastuzumab emtansine and pertuzumab, and some types of immunotherapy, can cause changes in the way the heart works. This is particularly the case if you already have heart disease.

If heart problems happen during treatment, your treatment may need to be paused or changed. Heart problems are usually temporary. This means they improve with medicine and get better after treatment ends.

An early menopause

Having an early menopause because of your treatment may increase the risk of heart problems. This is because oestrogen and progesterone help protect the heart.

Possible symptoms of heart problems

Possible symptoms of heart problems include:

  • feeling your heart beating fast, hard or irregularly
  • pain or discomfort in your chest
  • getting breathless – for example, when climbing stairs
  • feeling weak or dizzy
  • getting tired very easily
  • swollen feet and lower legs.

These symptoms can be caused by lots of other things. But it is still important to tell your GP, cancer doctor or specialist nurse straight away if you develop any. If you get symptoms many years after treatment, you may need to tell your doctor or nurse which cancer treatments you have had. This will help them find the right help for you.

If you have heart problems, your doctor will refer you to a heart specialist (cardiologist).

What you can do to keep your heart healthy

Making small changes to your lifestyle may help reduce your risk of developing heart problems. Here are some things that can help:

  • keep active
  • eat healthily
  • drink less alcohol
  • stop smoking.

If you already have heart problems, small changes can help to reduce your risk of further problems. The British Heart Foundation has lots of information and advice about keeping your heart healthy.

Effects on the lungs after breast cancer treatment

Some treatments for breast cancer can affect the lungs. Signs of lung problems include:

  • feeling breathless
  • having a cough
  • pain in the chest.

It is important to let your cancer doctor, specialist nurse or GP know straight away if you have symptoms. They will check what is causing your breathlessness and give you medicines and advice on how to manage it. They may arrange some tests or scans.

If you are still having treatment, it may need to be delayed or changed.


Radiotherapy can change the cells that line the lungs. It can cause a hardening and thickening of the tissue. This is called fibrosis. This can cause breathlessness months or years after treatment ends. But this is rare because radiotherapy is carefully planned and ways of giving it have improved.

The symptoms can be worse if you already have a chest problem such as asthma, or if you smoke.

Inflammation of the lung can occur 1 to 3 months after radiotherapy. This is called radiation pneumonitis. It causes symptoms such as:

But the condition usually improves and the symptoms go away.

Always talk to your cancer doctor, specialist nurse or GP if you develop new symptoms.

Targeted therapy and immunotherapy

Some targeted therapy and immunotherapy drugs used to treat breast cancer can affect the lungs.

Effects on the lungs due to targeted therapy and immunotherapy drugs usually happen within 3 months after treatment starts. Sometimes they can happen up to 1 year after treatment ends. You may have tests before, during and after treatment to check your lungs.

Side effects can include:

  • a cough
  • breathlessness
  • wheezing
  • a fever, with a temperature over 37.5˚C (99.5˚F).

You should contact your cancer doctor, specialist nurse or GP straight away if you notice any of these changes during treatment or after treatment has finished. You should also tell them if any existing breathing problems get worse. You may need steroids or other treatments to help.

Treatment for lung problems

Treatment will depend on the cause of your lung problems. You may be given steroids. These can be given as tablets, as an injection into a vein or as inhalers to reduce inflammation. You may be given inhalers that contain drugs to help open up the airways. These are called bronchodilators.

If you have an infection in the lung, you will be given antibiotics. Your breast cancer treatment may be delayed until symptoms are manageable.

What you can do to keep your lungs healthy

Making small changes to your lifestyle can reduce your risk of developing lung problems. Your cancer doctor, specialist nurse or GP can also give you advice and support about this. They may also refer you to a lung doctor called a respiratory specialist.

Asthma and Lung UK has lots of information and advice.

  • Stop smoking

    If you smoke, the most important thing you can do is to stop. It is also important to avoid being exposed to other people’s smoke. This is called passive smoking. Stopping smoking has lots of benefits.

  • Keep to a healthy weight

    Keeping to a healthy weight improves breathing problems.

  • Do some breathing exercises

    You can ask to be referred to a physiotherapist. They can teach you deep breathing exercises and give you advice on exercise. This can help you breathe better and improve breathlessness.

About our information

  • References

    Below is a sample of the sources used in our late effects of breast cancer information. If you would like more information about the sources we use, please contact us at cancerinformationteam@macmillan.org.uk

    Curigliano et al 2020. Management of cardiac disease in cancer patients throughout oncological treatment: ESMO consensus recommendations. Annals of Oncology. Vol 31 (2). Available from: www.annalsofoncology.org/article/S0923-7534(19)36080-6/pdf [accessed November 2021].

    Fabi et al 2020. Cancer-related fatigue: ESMO Clinical Practice Guidelines for diagnosis and treatment. Annals of Oncology. Available from: www.annalsofoncology.org/article/S0923-7534(20)36077-4/pdf [accessed November 2021].

    National Institute for Health and Care Excellence (NICE). Early and locally advanced breast cancer: diagnosis and management. NG101. Available from: www.nice.org.uk/guidance/ng101 [accessed November 2021].

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Dr Rebecca Roylance, Consultant Medical Oncologist and Professor Mike Dixon, Professor of Surgery and Consultant Breast Surgeon.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

The language we use

We want everyone affected by cancer to feel our information is written for them.

We want our information to be as clear as possible. To do this, we try to:

  • use plain English
  • explain medical words
  • use short sentences
  • use illustrations to explain text
  • structure the information clearly
  • make sure important points are clear.

We use gender-inclusive language and talk to our readers as ‘you’ so that everyone feels included. Where clinically necessary we use the terms ‘men’ and ‘women’ or ‘male’ and ‘female’. For example, we do so when talking about parts of the body or mentioning statistics or research about who is affected.

You can read more about how we produce our information here.

Date reviewed

Reviewed: 01 July 2023
Next review: 01 July 2026
Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

This means it is easy to use, up-to-date and based on the latest evidence. Learn more about how we produce our information.