Radiation therapy uses high energy x-rays to destroy cancer cells. A radiation oncologist will customize the treatment dose for individual needs. The goal is to try and kill as much cancer while minimizing harm to healthy tissue. Radiation therapy is generally most effective when used in combination with other treatments, such as surgery and chemotherapy. Radiation therapy for breast cancer is often used after surgery to target any possible remaining cancer cells. It may also be used to shrink large tumors that are causing symptoms.

There are different types of radiation therapy, but external beam radiation is more commonly used to treat breast cancer.

External Beam Radiation Therapy

In external beam radiation therapy, radiation is produced by a machine positioned outside the body. Short bursts of x-rays are directed at the cancer to affect as much cancer as possible. The radiation oncologist will determine how many treatments you will receive.

In general, radiation therapy is recommended:

  • After breast-conserving surgeries—radiation is aimed at the entire breast to try to destroy any remaining cancer tissue
  • After mastectomy—if the tumor was 5 centimeters or more in size OR 4 or more cancer-positive lymph nodes were found in the underarm
  • As comfort care for advanced or metastatic breast cancer
Radiation of a Tumor
Diagram of partial or segmental mastectomy
Copyright © Nucleus Medical Media, Inc.

Newer types of 3-dimensional (3-D) technology include intensity modulated treatment (IMRT) and conformal radiation therapy. The beams surround all sides of the tumor. This allows for more intense radiation to be delivered to the tumor. It also decreases the amount of damage to surrounding healthy tissue and has fewer side effects. These therapies are still being studied and may not be available in all areas.

Generally, external beam radiation only takes a few minutes, and the total treatment time can range from 5-8 weeks, depending on the total dose required. In most cases, radiation is given 5 days a week. For some, an accelerated treatments may be an option. This approach is known as hypofractionated radiation therapy and allows for more intense radiation less days per week for a shorter duration of time.


Brachytherapy, or internal radiation therapy delivers radiation directly to the cancer. The radioactive material is implanted inside the body near or in the cancer tumor.

Brachytherapy options include:

  • Intracavitary—A catheter with a radiation device is placed and secured at the location where a tumor was removed. The device is left in place until the course of radiation therapy is complete. During this time, the catheter will visible because it sticks out of the breast. This is the more common method.
  • Interstitial—Catheters are inserted in to the breast near the location where a tumor was removed. Pellets are placed into the catheter for a period of time each day, then are taken out. This approach is not used as often as it used to be.

Side Effects and Management

Complications of radiation therapy to the chest may include:

  • Cough
  • Shortness of breath
  • Blood in the sputum
  • Chest pains
  • Inflammation of the lung tissue—radiation pneumonitis

A variety of treatments are available to help manage side effects of radiation therapy, such as dry, irritated skin, nausea, vomiting, diarrhea, and fatigue due to anemia. Sometimes adjustments to treatment doses may also be possible. The earlier side effects are addressed, the more likely they will be controlled with a minimum of discomfort.

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