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Partial breast radiation therapy - external beam

Carcinoma of the breast - partial radiation therapy; Partial external beam radiation - breast; Intensity-modulated radiation therapy - breast cancer; IMRT - breast cancer WBRT; Adjuvant partial breast - IMRT; APBI - IMRT; Accelerated partial breast irradiation - IMRT; Conformal external beam radiation - breast


Partial breast radiation therapy uses high-powered x-rays to kill breast cancer cells. It is also called accelerated partial breast radiation (APBI). A standard course of external beam breast treatment takes up to 6 weeks. APBI can be accomplished in as little as 2 weeks. APBI targets a high dose of radiation on the area where the breast tumor was removed. It avoids exposing the surrounding tissue to radiation. There are three common approaches for APBI:

  • External beam, the topic of this article
  • Brachytherapy (inserting radioactive sources into the breast)
  • Intra-operative radiation (delivering radiation at the time of surgery in the operating room)



Radiation therapy is usually delivered on an outpatient basis.

Two common techniques are used for partial breast external beam radiation treatment:

  • Conformal external beam radiation
  • Intensity-modulated radiation therapy (IMRT)

Before you have any radiation treatment, you will meet with the radiation oncologist. This person is a doctor who specializes in radiation therapy.

  • The doctor will put small marks put on your skin. These marks ensure that you are correctly positioned during your treatments.
  • These marks will either be ink marks or a permanent tattoo. Do not wash ink marks off until your treatment is finished. They will fade over time.

The treatment is usually given 5 days a week for anywhere from 2 to 6 weeks. It may sometimes be given twice a day (usually with 4 to 6 hours between sessions).

  • During each treatment session you will lie on a special table.
  • The technicians will position you so the radiation targets the treatment area.
  • You may be asked to hold your breath while the radiation is being delivered. This helps limit how much radiation your heart receives.
  • Most often, you will receive radiation treatment for between 1 and 5 minutes. You will be in and out of the cancer center within 15 to 20 minutes on average.

Rest assured, you are not radioactive after these radiation treatments. It is safe to be around others, including babies or children.


Why the Procedure Is Performed


APBI is used to prevent breast cancer from coming back. When radiation therapy is given after breast-conserving surgery, it is called adjuvant (additional) radiation therapy.

APBI may be given after lumpectomy or partial mastectomy (called breast-conserving surgery) for:

  • Ductal carcinoma (DCIS)
  • Stage I or II breast cancer


Before the Procedure


Tell your health care provider what medicines you are taking.

Wear loose fitting clothes to the treatments.


After the Procedure


Radiation therapy can also damage or kill healthy cells. The death of healthy cells can lead to side effects. These side effects depend on the dose of radiation and how often you have the therapy. Radiation can have short term (acute) or long term (later) side effects.

Short-term side effects can begin within days or weeks after treatment begins. Most side effects of this type go away within 4 to 6 weeks after treatment ends. Most common short-term effects include:

  • Breast redness, tenderness, sensitivity
  • Breast swelling or edema
  • Breast infection (rare)

Long-term side effects may begin months or years after treatment and may include:

  • Decreased breast size
  • Increased firmness of breast
  • Skin redness and discoloration
  • In rare cases, rib fractures, heart problems (more likely for left breast radiation), or development of second cancer
  • Arm swelling (edema) - more common if the armpit area was treated

Your health care providers will explain care at home during and after radiation treatment.


Outlook (Prognosis)


Partial breast radiation following breast conservation therapy reduces the risk of cancer coming back, and possibly even death from breast cancer.




National Cancer Institute. Breast cancer treatment (PDQ). Cancer.gov Web site. Updated August 11, 2016. www.cancer.gov/types/breast/hp/breast-treatment-pdq . Accessed September 13, 2016.

National Cancer Institute. Radiation therapy and you: support for people who have cancer. Cancer.gov Web site. www.cancer.gov/publications/patient-education/radiation-therapy-and-you . Accessed September 13, 2016.


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              Review Date: 9/28/2016

              Reviewed By: David Herold, MD, MBA, radiation oncologist in West Palm Beach, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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