Radiotherapy treats cancer by using high-energy rays to destroy the cancer cells, while doing as little harm as possible to normal cells. The treatment is often used after surgery for breast cancer, most commonly after surgery to remove part of the breast (lumpectomy or segmental excision) but also in some cases following mastectomy. It may occasionally be used before, or instead of, surgery.

How it’s given

The treatment is given in the radiotherapy department in Cork University Hospital as a series of short daily sessions. The treatments are given from Monday to Friday, with a rest at the weekend. Each treatment takes 10–15 minutes. A course of radiotherapy for breast cancer is provided on an outpatient basis and may last from 3–6 weeks.

Radiotherapy can cause side effects such as skin soreness and tiredness, but most symptoms will improve once treatment has finished. Sometimes radiotherapy can cause long-term side effects.

External radiotherapy does not make you radioactive and it's perfectly safe for patients to be with other people, including children, after treatment.

When it’s used

If part of the breast has been removed (termed lumpectomy or wide local excision) radiotherapy is routinely given to the remaining breast tissue to reduce the risk of the cancer coming back in that area. The radiotherapy is normally given to the whole breast area, and may also include the underarm (axilla), and the area around the collarbone and at the top of the chest by the breast bone (sternum), where there are lymph nodes.

After a mastectomy| radiotherapy to the chest wall may be given if the risk of the cancer coming back in that area is felt to be likely.

If a few lymph nodes have been removed and these contained cancer cells, or if no lymph nodes have been removed, radiotherapy may be given to the armpit to treat the remaining lymph nodes. If all the nodes have been removed from under the arm, radiotherapy to the armpit is not usually needed.

Some women may have an extra dose given to the area of the breast where the cancer was. This is known as a boost. This usually involves 4-8 further treatments.