Radiation Therapy for Breast Cancer

Radiation therapy involvesdelivering precise amounts of high-energy radiation to kill cancer cells. The radiation stops the reproduction of cancer cells while minimizing damage to healthy tissues. Radiation therapy has been shown to improve survival in women with breast cancer.

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Radiation therapy for breast cancer can be used:

  • After lumpectomy or mastectomy, either alone or in combination with chemotherapy and/or hormone therapy, to reduce the risk of cancer recurring in the breast
  • As the main treatment for breast cancer if the surgeon believes the tumor cannot be safely removed, if a woman's health does not allow surgery, or if the woman chooses not to have surgery
  • To treat cancer that has spread into the bones or the brain
  • To relieve pain or other problems if the cancer recurs.

Types of Radiation Therapy for Breast Cancer

The type of breast cancer radiation that most people are familiar with is called external beam radiation. It's also the type most commonly used in cases of breast cancer. External beam radiation works by focusing a beam of radiation from a machine to its target, the area of the body affected by cancer.

The other type of breast cancer radiation is called brachytherapy. The main types of brachytherapy deliver radiation to the cancer internally using an implant. In the case of breast cancer, radioactive seeds or pellets -- as small as grains of rice -- are placed inside the breast near the cancer using a tube or small catheter. A non-invasive type of brachytherapy can give a radiation boost dose at the surgical excision site. Brachytherapy can be used alone or with external beam radiation. Tumor size, location, and other factors will determine if someone is a candidate for this type of radiation.

External Beam Radiation Therapy Side Effects

Radiation therapy is painless. However, some women experience side effects, which can include:

  • Redness, discomfort, dryness, and blistering of the skin in the treated area; your doctor will recommend a specific treatment if this happens. The redness can take as long as a year to fade.
  • Fatigue, usually starting two to three weeks after treatment begins; the fatigue increases during the duration of treatment and goes away about a month after treatment ends. Fatigue should not disable you. Most women cope by taking a nap or by going to bed earlier.
  • Reduced blood counts; your blood will be checked regularly, especially if you are also receiving chemotherapy.
  • Smaller, firmer breasts, which may affect options for breast reconstruction

  • Lymphedema, or swelling, if axillary (armpit) lymph nodes are irradiated



Brachytherapy has side effects similar to those with external beam radiation, including redness, bruising, breast pain , infection, weakness , and an increased risk of fractured ribs.

For more information about possible side effects, see Side Effects of Cancer Drugs and Radiation.

During radiation therapy for breast cancer, women should:

  • Contact the doctor if they develop unusual symptoms, such as coughing, sweating, fever, or unusual pain.
  • Get enough rest and eat a healthy diet.
  • Go for regular blood tests as required by the doctor.
  • Be extra kind to the involved area. Avoid tight clothes or anything that rubs.
  • Protect the area from exposure to the sun.
  • Apply moisturizing creams after radiation is complete.

Many advances in radiation therapy for breast cancer have helped women avoid long-term side effects. However, they can happen and include:

  • Rib fractures, which tend to heal without treatment (less than 1%)
  • Lung inflammation, which tends to resolve on its own (less than 1%)
  • Damage to the heart (Older methods of radiation therapy caused more problems. New advances avoid direct radiation to the heart.)
  • Scarring
  • Very rarely, radiation therapy may be associated with causing other tumors such as angiosarcoma.


WebMD Medical Reference Reviewed by Laura J. Martin, MD on July 30, 2017



American Cancer Society. 

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