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About Breast Cancer > Treatment > Radiation Treatment

Radiotherapy for Breast Cancer

What is radiotherapy?
Radiotherapy is a treatment to kill cancer cells using ionizing radiation. Radiation is capable of producing damage at the DNA level of a cell and can stop cells from reproducing.

How does radiotherapy work?
Radiotherapy works by killing breast cancer cells directly on exposure to the radiation beam. Normal human cells are able to recover from radiation damage to a much more efficient degree than cancer cells. Therefore, radiation treatment is able to kill cancer cells selectively while allowing normal cells to recover.

When is radiotherapy given?
In most cases, radiotherapy treatment can be given after surgery or chemotherapy. It is a procedure to destroy any cancer cells that may remain and it helps reduce the risk of recurring.

Who needs radiotherapy? For breast cancer patients, radiotherapy treatment to the breast is needed when the tumour is treated by breast conserving surgery (local excision of the tumour and axillary lymph node surgery preserving the breast). This applies to all patients with invasive breast cancer and most patients with in-situ cancer. Radiotherapy is also needed by some patients who have mastectomy, if the tumour is locally advanced like large tumour size or with multiple lymph nodes showing cancer, or where cancer cells are formed in lymphatic or blood vessels These indications are irrespective of whether the patient to receive chemotherapy or hormonal therapy as well.

How is it carried out?
Usually at about 3 to 4 weeks after breast surgery, or after completion of chemotherapy if such is needed, the patient is ready for radiotherapy. Before starting the treatment, the patient will visit the radiotherapy centre, where “planning” (i.e. preparation of treatment) is done. The planning is an initial simulation procedure which will usually take about 45 - 60 minutes. The patient will be positioned on a special couch with arms raised and supported. The oncologist will use a special X ray machine called the simulator to "sketch out" the target of treatment (the breast, and in some cases, the regional lymphatics as well). A CT scan planning procedure is currently used in many patients. Marks are put on the skin to direct the radiation beams. These marks are small and patient is advised to be careful not to wash them off during the treatment period. In some cases, the marks may be permanent (tattoo). The treatment is delivered daily. There shall be around 25 to 30 treatments. It is usually over a period of 5 to 6 weeks.

What are the likely side effects?
Radiotherapy does not make patients radioactive. Receiving radiotherapy is painless and side effects of radiotherapy are site-related only. Loss of hair, mouth ulcers, dry mouth, vomiting or diarrhea will not occur in breast cancer patients receiving radiotherapy to the breast, chest wall or axilla. The likely side effects of radiotherapy are:

During radiotherapy:
Erythema: The skin on the breast will become red and dry, much like sunburn. This can begin from the second week of treatment, and usually improves a few weeks after completing treatment.

Nursing tips:
  • Protect the skin in the radiated area from physical or chemical damage during the course of treatment.
  • Do not rub the radiated area but gently pat the skin dry after wash.
  • Bathing is not recommended.
  • Avoid using deodorants, perfumes, oil or talcum powder (baby powder).
  • Avoid products that contain alcohol or menthol as they remove natural lipids and worsen skin’s reaction.
  • Avoid adhesives.
  • Avoid extremes of temperatures around the radiated areas, such as hot water packs or ice packs.
  • Do not expose the radiated area to the sun.
  • Protect radiated area from injury. Avoid wearing tight clothing, bra and jewelry.


Desquamation: The radiated skin may start to peel or blister towards the middle or end of the treatment as the skin’s epithelial barrier becomes loosened by the radiation. This usually settles within weeks of completing treatment.

Nursing tips:
  • Follow the above nursing tips and inform oncologist.
  • Follow oncologist’s advice and apply topical hydrogel or cream if prescribed. Dressing may be needed for moist desquamation.


Tiredness: Patient will probably start to feel tired about a week or so after starting radiotherapy. This may last for a few weeks after completing the treatment. Observe body’s reaction and take rest if necessary.

Darker skin: The radiated area looks darker than usual. It may last for a few months after completing treatment, but the colour will fade with time.

After radiotherapy

  • The breast will become firmer in the first year after radiotherapy treatment, and it will usually become softer again.
  • Patients who require radiotherapy to the axilla where surgery has been performed, a certain degree of swelling (lymphoedema) of the arm may occur. Patients are advised to consult oncologist or nurse for lymphoedema prevention.
  • In very rare cases patients may develop pneumonitis (inflammations of the lungs) after completion of radiotherapy.
  • Patients who have radiotherapy to the left side of their chest may have effects on their heart many years later. However, with the advancement of planning and treatment techniques, this side effect may be much reduced or avoided altogether. Often symptoms will not be caused to patients.

Special thanks to Dr. Peter Choi for editing

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