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Radiotherapy for primary breast cancer

Radiotherapy is a treatment for cancer that uses carefully measured and controlled high energy x-rays. In primary breast cancer it aims to destroy any cancer cells that may be left behind in the breast area after surgery.

The following information explains how radiotherapy is used to treat people with primary breast cancer. If you have secondary breast cancer, you can read our information about treating secondary breast cancer.

What is radiotherapy?

Radiotherapy treats the site where the cancer started.

X-rays are produced by a machine called a linear accelerator (often referred to as a linac), which focuses on the exact area to be treated. There's an illustration of a linear accelerator below.


Radiotherapy also affects healthy tissue in the area being treated. However, this is generally able to recover and repair itself. It’s given in such a way that it has the greatest effect on the cancer cells while limiting the damage to normal healthy tissue.

Radiotherapy is a specialised treatment and is not available in every hospital. However, each breast unit is linked to a hospital that has a radiotherapy department where you’ll be treated as an outpatient.

Find out how radiotherapy is given.

Why may I need radiotherapy?

Radiotherapy is given after surgery to reduce the risk of the cancer returning in the breast area. You may hear this called adjuvant (additional) therapy.

Whether you’re offered radiotherapy will depend on your individual situation. When deciding on the best treatment, your oncologist (cancer specialist) will consider factors such as the location, grade, size and stage of your cancer.

When will I have radiotherapy?

Your specialist or breast care nurse can tell you when you can expect to start your radiotherapy.

Radiotherapy is given after surgery. If you’re having chemotherapy after surgery, radiotherapy can be given towards the end of chemotherapy or, more commonly, after chemotherapy has finished.

National guidance recommends you shouldn’t have to wait more than 31 days in England, four weeks in Wales or 42 days in Scotland between surgery or the end of chemotherapy and the start of radiotherapy.

However, some people have to wait longer than this. Radiotherapy can also be delayed for a medical reason, such as waiting for a surgical wound to heal.

You’ll first see the oncologist in the outpatient department to talk about your treatment. Once the treatment, its benefits, risks and potential side effects have been fully explained to you, you’ll be asked to sign a consent form. A further appointment is then made to plan your treatment.

Which areas are treated?

The exact area to be treated will be worked out during your treatment planning.

The sequence and timing of radiotherapy will depend on your individual situation and any other treatment you are having.

After breast-conserving surgery

If you had breast-conserving surgery (the removal of the cancer and an area of normal breast tissue around the cancer) you’ll usually be given radiotherapy to the remaining breast tissue on that side.

After a mastectomy

If you had a mastectomy (complete removal of the breast), you may be given radiotherapy to the chest in the area where you had your surgery. This may be done for a number of reasons, for example because:

  • the tumour was large
  • the tumour was near the chest wall or deep within the breast tissue
  • there’s a high risk that cancer cells may have been left behind
  • cancer cells are found in the lymph nodes (glands) under the arm (axilla).

Radiotherapy to the lymph nodes

Sometimes the lymph nodes under the arm and above the collarbone (clavicle) will also be treated with radiotherapy. This will depend on the type of surgery you’ve had and whether the under arm lymph nodes contained cancer cells. Your oncologist will discuss this with you.

Getting to and from appointments

Most people feel able to drive themselves to and from their regular radiotherapy appointments. Whether you drive or use public transport, travelling to your treatment can be expensive, but help may be available.

If you come by car, you may be able to have a special hospital pass which means you won’t have to pay car parking fees while having radiotherapy. If you claim benefits or are on a low income, you may be entitled to help with petrol costs or bus or train fares. Alternatively, there may be community transport services in your area or organisations with volunteer drivers who give people lifts to and from hospital.

Macmillan Cancer Support produces a booklet called Help with the cost of cancer which outlines what you may be entitled to. The NHS leaflet Help with health costs (HC11) may also be useful.

If you think going to appointments will be difficult because of the cost or other travel issues, talk to your radiographer or breast care nurse to find out what help might be available. If you have a local cancer information centre, they may be able to tell you if any financial help or voluntary community transport is available in your area.

Questions you may want to ask your oncologist

  • Why are you recommending radiotherapy?
  • What are the benefits and risks?
  • What are the side effects?
  • Are there any other treatments I could have?
  • Which area(s) will be treated?
  • How long will the radiotherapy take and how often will each treatment be given?
  • How long will I have to wait before starting treatment?
  • Will having radiotherapy affect my reconstructed breast or my options for breast reconstruction in the future?
  • What is my risk of lymphoedema (swelling of the tissues of the arm or breast/chest)?
  • Are there any clinical trials for radiotherapy I could take part in?

Why may radiotherapy not be an option?

Radiotherapy may not be a treatment option for you if:

  • you have already had radiotherapy to that breast
  • you have a medical condition which makes you particularly sensitive to the effects of radiotherapy
  • you’re pregnant.

Content last reviewed June 2014; next planned review 2016