Please note - the information below, and in the rest of the radiotherapy section, is intended for those who have been diagnosed with primary breast cancer. If you are looking for more information about secondary breast cancer and when radiotherapy may be used, please visit our pages on treatments for secondary breast cancer.

What is radiotherapy?

Radiotherapy is the use of carefully measured and controlled high energy x-rays to destroy cancer cells. Treatment is given regularly over a period of time to have the greatest effect on the cancer cells while limiting the damage to normal cells.

Radiotherapy is a specialised treatment so isn’t available in every hospital. However, each breast unit is linked with a hospital that has a radiotherapy department.

Radiotherapy is used to treat breast cancer in a number of ways.

  • After surgery to get rid of any remaining cancer cells left behind in the breast area. This reduces the risk of the cancer coming back. If you have had breast-conserving surgery (such as a wide local excision or lumpectomy) you’ll usually have radiotherapy to the remaining breast tissue on that side. If you have a mastectomy, you may be given radiotherapy to the chest area. This is more likely to happen if the tumour was large, if there is a high risk that cancer cells may have been left behind or if cancer cells are found in the lymph nodes under the arm (axilla).
  • After surgery to treat the lymph nodes above the collarbone and in the armpit. This will depend on the surgery you’ve had and whether or not the lymph nodes contained cancer cells. If all the lymph nodes have been removed, you will not usually need radiotherapy to the area under the arm.

Radiotherapy may not be recommended as part of your treatment if:

  • you have already had radiotherapy to the breast
  • you have a medical condition that makes you particularly sensitive to its effects
  • you are pregnant.

Also, you may decide you don’t want to have radiotherapy.

When will I begin radiotherapy?

Once you have been assessed by your specialist team as being ready to receive radiotherapy, national guidance states that treatment should begin within 31 days of you agreeing to the treatment, unless there is a medical reason why it cannot be given, for example a wound infection. However, some people may have to wait a bit longer. Radiotherapy may also be delayed for medical reasons, such as waiting for a surgical wound to heal.

If you are also going to have chemotherapy as part of your treatment, radiotherapy is usually given after chemotherapy has finished.

Radiotherapy and breast reconstruction

Many women consider having breast reconstruction following mastectomy. This can be done at the same time as mastectomy (immediate reconstruction) or at a later date (delayed reconstruction). The type and timing of reconstruction will be affected if  radiotherapy is required as it can affect the elasticity and quality of the skin over the area treated.

Content last reviewed March 2012; next planned review 2013


Last edited:

29 November 2013