Having radiotherapy for breast cancer

Radiotherapy uses high energy x-rays to treat cancer cells. It is a common treatment for breast cancer. 

For breast cancer, you usually have a type of radiotherapy called external beam radiotherapy. This means using radiation from a machine to destroy the cancer. 

You usually have radiotherapy after surgery to lower the risk of the cancer coming back. You might also have it if you have secondary or advanced breast cancer. This means that the breast cancer has spread from the breast to different parts of the body such as the brain or bones. 

You have your treatment in the hospital radiotherapy department. You might have radiotherapy as a single treatment or a series of daily treatment sessions. A single dose of radiotherapy is called a fraction. A series of sessions make up a radiotherapy course.

You usually have radiotherapy from Monday to Friday with a break at the weekend. This is usually over 1 to 3 weeks depending on your situation.

You need to travel to the hospital each time you have treatment. Some hospitals have rooms nearby where you can stay if you have a long way to travel.

Radiotherapy after breast conserving surgery (lumpectomy)

After breast conserving surgery, you might have one of the following:

  • radiotherapy to the whole breast
  • radiotherapy to a part of the breast (partial breast radiotherapy)

Your doctor can tell you whether you need radiotherapy to the whole breast, or only to a part of the breast. This depends on the risk of your cancer coming back. 

You generally start radiotherapy about 4 to 8 weeks after surgery.

If you need to have chemotherapy you have this before your radiotherapy. 

Radiotherapy after removal of the breast (mastectomy)

You may have radiotherapy after a mastectomy if there is a high risk of the cancer coming back. 
Your doctor may suggest you have it if:

  • you have cancer cells in the lymph nodes in the armpit (axilla)
  • cancer cells are seen close to the removed breast tissue
  • the cancer is large

Radiotherapy to the lymph nodes

The lymph nodes Open a glossary item in your armpit will need treatment if a biopsy Open a glossary item shows that one or more lymph nodes contain cancer cells. The treatment is usually surgery to remove the lymph nodes in the armpit. You may also have radiotherapy to the lymph nodes above the collarbone or around the breastbone. 

Radiotherapy breast boost

You may also have a boost of radiotherapy to the breast. A boost is an extra amount (dose) of radiotherapy targeted at the area in the breast where the cancer was removed.

You might have this if you have had your whole breast treated with radiotherapy after breast conserving surgery. It helps reduce the risk for people who have a higher risk of the cancer coming back.  

You may have 4 to 5 radiotherapy boosts at the end of the treatment to your breast.

Not everyone needs radiotherapy boosts. Your doctor will tell you if it’s suitable for you.

Radiotherapy for secondary breast cancer

Radiotherapy is helpful for treating breast cancer that has spread to different parts of the body. This is secondary or advanced breast cancer. The treatment can usually shrink the cancer and help relieve any symptoms you may have.

Radiotherapy to treat breast cancer that has spread to the bones

You usually have one fraction or treatment to the areas of the bone where the breast cancer has spread. It can help strengthen the bone and relieve pain. You may not notice the benefit straight away, as it can take some days for the treatment to work.  

Radiotherapy to treat breast cancer that has spread to the brain

For breast cancer that has spread to the brain, you might have surgery followed by radiotherapy. Or your doctor may suggest you have radiotherapy on its own. 

It is usual to have some side effects after treatment, these can include feeling weak and sickness. 

Radiotherapy to treat spinal cord compression

Spinal cord compression happens when breast cancer spreads to the bones in the spine causing pressure on the spinal cord Open a glossary item. Radiotherapy reduces pressure on the spinal cord by targeting and destroying the cancer cells. 

Pain in your back, spine or neck is often the first symptom. Spinal cord compression is an emergency and needs to be treated quickly. Contact your doctor straight away if you have any symptoms of spinal cord compression.

Planning radiotherapy

Before you start radiotherapy treatment, you have an appointment to plan your treatment.

The radiotherapy room

Radiotherapy machines are very big and could make you feel nervous when you see them for the first time. The machine might be fixed in one position. Or it might rotate around your body to give treatment from different directions. The machine doesn't touch you at any point.

Before your first treatment, your therapy radiographers Open a glossary item will explain what you will see and hear. In some departments, the treatment rooms have docks for you to plug in music players. So, you can listen to your own music while you have treatment.

Photo of a linear accelerator

Before each treatment session

The radiographers help you to get onto the treatment couch. You lie on a special board called a breast board. If you have had a shell (mould) made the radiographers will fix this in place. You might need to raise your arms over your head.

The radiographers line up the radiotherapy machine using the marks on your body or on the shell. Once you are in the right position, they leave the room.

It is important to continue the arm exercise you were shown after your surgery. This helps to stop your arm and shoulder from becoming stiff during your radiotherapy treatment.

During the treatment

You need to lie very still. Your radiographers might take images (x-rays or scans) before your treatment to make sure that you're in the right position. The machine makes whirring and beeping sounds. You won’t feel anything when you have the treatment.

Your radiographers can see and hear you on a CCTV screen in the next room. They can talk to you over an intercom and might ask you to hold your breath or take shallow breaths at times. You can also talk to them through the intercom or raise your hand if you need to stop or if you're uncomfortable.

This video shows you what happens, it is 1 minute 22 seconds long.

Breathing technique

You might need to hold your breath at times during the treatment if you have radiotherapy to your left breast. This is to protect your heart from the radiotherapy.

The radiographer talks to you over a speaker. They tell you when to hold your breath. It could last up to 20 seconds. This technique is called deep inspiration breath hold (DIBH).

You can also have a shield placed over the heart to protect it if you can't tolerate DIBH.

You won't be radioactive

This type of radiotherapy won't make you radioactive. It's safe to be around other people, including pregnant women and children.

Travelling to radiotherapy appointments

You might have to travel a long way each day for your radiotherapy. This depends on where your nearest cancer centre is. This can make you very tired, especially if you have side effects from the treatment.

You can ask the therapy radiographers Open a glossary item for an appointment time to suit you. They will do their best, but some departments might be very busy. Some radiotherapy departments are open from 7 am till 9 pm.

Car parking can be difficult at hospitals. Ask the radiotherapy staff if you are able to get free parking or discounted parking. They may be able to give you tips on free places to park nearby.

Hospital transport may be available if you have no other way to get to the hospital. But it might not always be at convenient times. It is usually for people who struggle to use public transport or have any other illnesses or disabilities. You might need to arrange hospital transport yourself.

Some people are able to claim back a refund for healthcare travel costs. This is based on the type of appointment and whether you claim certain benefits. Ask the radiotherapy staff for more information about this and hospital transport.

Some hospitals have their own drivers and local charities might offer hospital transport. So do ask if any help is available in your area.

Side effects of treatment

Radiotherapy for breast cancer can make you tired and might cause other side effects.

  • Early and locally advanced breast cancer: diagnosis and management
    National Institute for Health and Care Excellence (NICE), 2018. Last updated June 2023

  • Hypofractionated breast radiotherapy for 1 week versus 3 weeks (FAST-Foward): 5-year efficacy and late normal tissue effects results from a multicentre, non-inferiority, randomised, phase 3 trial 
    A M Brunt and others
    The Lancet, 2020. Vol 395, Issue 10237. Pages 1613-1626

  • Postoperative radiotherapy for breast cancer: hypofractionation RCR consensus statements
    The Royal College of Radiologists, 2021

  • Early breast cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up
    F Cardoso and others
    Annals of Oncology, 2019. Vol 30, Issue 8. Pages 1194-1220

  • Cancer: Principles and Practice of Oncology (12th edition)
    VT DeVita, TS Lawrence, SA Rosenberg
    Wolters Kluwer, 2023

  • The information on this page is based on literature searches and specialist checking. We used many references and there are too many to list here. Please contact patientinformation@cancer.org.uk with details of the particular issue you are interested in if you need additional references for this information.

Last reviewed: 
03 Jul 2023
Next review due: 
03 Jul 2026

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