Radiation therapy for breast cancer

Radiation therapy for breast cancer uses radiation, such as x-rays, to kill cancer cells or injure them so they cannot grow and multiply. When used as part of breast cancer treatment, it is recommended:

  • after breast conserving surgery to help destroy any undetected cancer cells that may be in the breast and to reduce the risk of the cancer coming back (adjuvant treatment)
  • sometimes after a mastectomy, depending on the risk of the cancer coming back in the chest area
  • if lymph nodes from under the arm were removed and the risk of the cancer coming back in this area is considered to be high.

You will usually start radiation therapy about four weeks after surgery. If you’re having chemotherapy after surgery, radiation therapy treatment will begin about four weeks after chemotherapy has finished.

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Planning radiation therapy

Treatment is carefully planned to have the greatest effect on the cancer cells and to limit the damage to the surrounding healthy body tissues. Planning consists of several steps, which may occur over a few appointments.

You will have a planning session at the radiation therapy centre. During this appointment, you will have a CT scan to pinpoint the area to be treated, and marks will be put on your skin so the radiation therapists treat the same area each time. These marks are small dots (tattoos) and they may be temporary or permanent. Talk to your radiation therapists if you are uncomfortable having a permanent tattoo.


Having radiation therapy

You will probably have radiation therapy daily from Monday to Friday for 4–6 weeks. In some cases, you may have a larger dose each day for about three weeks. Usually you can have radiation therapy as an outpatient and go to the treatment centre each day. If you live in a regional or rural area and need to travel for the treatment, you may be eligible for assistance with transport and accommodation costs.

Each radiation therapy session will be in a treatment room. Although you will only get radiation for 1–5 minutes, you might be in the treatment room for 10–30 minutes. Most of the time is spent positioning you and the treatment machine.

You will lie on a table under the radiation therapy machine. The radiation therapists will leave the room and then switch on the machine, but you can talk to them through an intercom. Radiation therapy is not painful, but you need to lie still while the treatment is given.


Side effects of radiation therapy

Radiation therapy may cause the following side effects:

  • Tiredness – You may feel tired or fatigued (lacking energy for day-to-day activities) 1–2 weeks after radiation therapy starts, and during treatment. This usually eases a few weeks after treatment finishes.
  • Red and dry skin – The skin at the treatment site may become red and dry after a few weeks of treatment. It usually returns to normal 4–6 weeks after treatment ends. Radiation therapy nurses will show you how to care for your skin. Sorbolene cream applied twice a day can be helpful.
  • Inflammation and blistering – Less commonly, your skin may become itchy and/or very irritated. This will be closely monitored by the treatment team, who will recommend creams you can apply to the area.
  • Aches and swelling – You may feel minor aches or shooting pains that last for a few moments during treatment. Some people develop fluid in the breast (breast oedema).

These changes to the breast may be ongoing for up to 12 months, but in some cases, they can last up to five years. Radiation therapy may also increase the chance of developing lymphoedema in the arm on the same side as the affected breast.

Talk to your doctor about any changes you experience. You will have regular appointments with your radiation oncologist and radiation therapy nurse throughout your treatment.

Radiation therapy to the breast does not cause you to lose hair from your head, although you may lose hair from the treated armpit. 

The radiation will not make you radioactive because the radiation does not stay in your body during or after treatment, and so it is safe for you to spend time with friends and family.

For ways to deal with side effects, read Understanding Radiation Therapy.


Video: What is radiation therapy?

Watch this short video to learn more about radiation therapy.


This information was last reviewed in July 2016
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Cancer information

What is radiation therapy?
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