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Radiation therapy for breast cancer uses high-powered X-rays to kill cancer cells. Rapidly growing cells, such as cancer cells, are more susceptible to the effects of radiation therapy than are normal cells.

One of two approaches may be used with radiation therapy for breast cancer:

External radiation. External beam radiation, the standard type of radiation therapy, delivers radiation in the form of high-powered energy beams, such as X-rays, to your entire breast from a machine outside your body. This is the most common type of radiation therapy used for breast cancer.

Internal radiation. Internal radiation (brachytherapy) involves temporarily placing small radioactive devices in your breast near the tumor site to deliver radiation to affected breast tissue. Internal radiation may be used as an extra radiation boost after external radiation or for small, contained tumors.

Radiation therapy may be used to treat breast cancer at almost every stage. It’s an effective way to reduce your risk of breast cancer recurring after surgery. It can also help control the spread of breast cancer and offer pain relief for advanced breast cancer.

Radiation After Lumpectomy

Radiation therapy for breast cancer is almost always recommended after surgery that removes only the tumor (lumpectomy). A lumpectomy alone, without radiation therapy, carries a relatively high risk of cancer recurrence in the affected breast months or years later because of microscopic deposits of cancer left behind after surgery. Radiation helps to destroy remaining cancer cells.

Lumpectomy combined with radiation therapy is often referred to as breast-conservation therapy. In clinical trials comparing lumpectomy with and without radiation therapy, the addition of radiation therapy after a lumpectomy resulted in significantly decreased rates of breast cancer recurrence and proved to be as effective as having the entire breast removed.

Radiation After Mastectomy

Removal of the entire breast (mastectomy) usually means you won’t need radiation therapy. But radiation therapy is sometimes recommended for women at high risk of cancer recurrence. Factors that may put you at high risk of breast cancer recurrence in your chest wall include:

Lymph nodes with signs of breast cancer. Underarm (axillary) lymph nodes that test positive for cancer cells are an indication that some cancer cells have spread from the primary tumor. The more positive nodes you have, the more likely your doctor is to recommend radiation therapy. Experts agree that having four or more positive nodes is a clear indication for radiation therapy after mastectomy, although data suggest that even women with fewer positive lymph nodes may benefit from radiation therapy.

Large tumor size. A tumor greater than 5 centimeters (about 2 inches) generally carries a higher risk of recurrence than do smaller tumors.

Tissue margins with signs of breast cancer. After breast tissue is removed, the margins of the tissue are examined for signs of cancer cells. Very narrow margins or margins that test positive for cancer cells are a risk factor for recurrence.

Radiation for locally advanced breast cancer

Radiation therapy can also be used to treat:

  • Breast tumors that cannot be surgically removed.
  • Inflammatory breast cancer, an aggressive type of breast cancer that spreads to the lymph channels of the skin covering the breast. People who have this type of breast cancer typically receive chemotherapy before a mastectomy, followed by radiation, to decrease the chance of recurrence.
  • Radiation for managing metastatic complications

If breast cancer has spread to other parts of your body (metastasized) and a tumor is causing pain or some other symptom, radiation can be used to shrink the tumor and ease that symptom.


Both external and internal radiation therapy have potential side effects:

External radiation therapy

  • Mild to moderate fatigue (fatigue tends to increase over the course of treatment)
  • Skin irritation — such as itchiness, redness, peeling or blistering — similar to what you might experience with a sunburn (skin irritation tends to increase over the course of treatment)
  • Breast swelling
  • Changes in skin sensation

Rarely, radiation therapy may cause:

  • Arm swelling (lymphedema)
  • Rib fracture or chest wall tenderness
  • Inflamed lung tissue
  • Heart damage
  • Secondary cancers, such as bone or muscle cancers (sarcomas) or lung cancer

Internal radiation therapy

Internal radiation therapy usually produces fewer skin reactions, although the treated area may be sore and tender for a few months after treatment.

Other possible side effects include:

  • Bruising
  • Infection
  • Rib fracture or chest wall tenderness

How To Prepare

You’ll meet with your radiation therapy team, health care professionals who work together to plan and provide your radiation treatment. Team members usually include:

  • A radiation oncologist, a doctor who specializes in treating cancer with radiation. He or she determines the appropriate therapy for you, follows your progress and adjusts your treatment, if necessary.
  • A radiation physicist and a dosimetrist, who make calculations and measurements regarding your radiation dosage and its delivery.
  • A radiation oncology nurse, who can answer questions about the treatments and side effects, and help you manage your health during treatment.
  • A radiation therapist, who operates the radiation equipment and administers your treatments.
  • Your radiation oncologist will review your medical history with you and give you a physical exam to check your overall health before you begin radiation therapy. Your oncologist can also discuss the potential benefits and side effects of your radiation therapy.

External radiation therapy

Before your first treatment session, you’ll go through a simulation in which a radiation oncologist carefully maps your breast area to pinpoint the precise location of your treatment. During the simulation:

  • A radiation therapist helps you into a position best suited to pinpoint the affected area and avoid damage to surrounding normal tissue. Sometimes pads or other devices are used to help you hold the position.
  • Using a CT scanner, the radiation oncologist locates the treatment area. You’ll hear noise from the CT equipment as it moves around you. Try to relax and remain as still as possible to help ensure consistent, accurate treatments.
  • Ink marks or tiny permanent tattoo dots are placed on your skin to guide the radiation therapist in administering the radiation. Be sure not to wash ink marks off until you’re told to do so. If the marks can’t be seen, you may need to go through the mapping process again.
  • The dosimetrist, radiation physicist and radiation oncologist use computer software to plan the dose of radiation you’ll receive. Once the simulation and planning are complete, you can begin treatment. For each session, avoid wearing jewelry, latex bandages, powder, lotion or deodorant on or near your treatment area. These substances can interfere with delivery of the radiation.
  • Internal radiation therapy

Before internal brachytherapy is started, a special device for the radioactive implants is placed in the area from where the tumor was taken (tumor bed). This may be done during your cancer surgery or as a separate procedure.

If the radiation device is implanted during a separate procedure, it often requires a brief hospital stay. You’ll be given local, regional or general anesthetic for the procedure. Once the holder is implanted, you can likely go home.

Internal radiation therapy

There are two approaches to internal radiation therapy for breast cancer:

Intracavitary brachytherapy. A small, deflated balloon attached to a thin tube (catheter) or a cage of small catheters is inserted in the tumor bed, with the end of the tubes sticking out of the breast. The balloon is filled with saline solution and left in place throughout the course of treatment. That’s where the radioactive implants are inserted.

Interstitial brachytherapy. Several small catheters are inserted in the breast around the tumor bed to serve as holders for small radioactive pellets. These catheters are generally left in place throughout the course of treatment.

What To Expect

The typical schedule for external radiation treatments is five days a week for four to six weeks. You’ll receive radiation as an outpatient at a hospital or other treatment facility. You may be able to schedule your sessions at the same time each day.

The duration of internal radiation therapy for breast cancer is much shorter, usually five days. Internal radiation sessions are typically done on an outpatient basis.

External radiation

A typical radiation therapy session generally follows this process:

  • When you arrive at the hospital or treatment facility, you’re taken to a special room that’s used specifically for radiation therapy.
  • You may need to remove your clothes and put on a hospital gown.
  • The radiation therapist helps you into the position you were in during the simulation process.
  • The therapist leaves the room and turns on the machine that delivers the radiation (linear accelerator).
  • Although the therapist isn’t in the room during the treatment, he or she will monitor you from another room on a television screen. Usually you and the therapist can talk through an intercom. If you feel sick or uncomfortable, tell your therapist, who can stop the process if necessary.
  • Delivery of the radiation lasts a few minutes, but expect to spend 15 to 30 minutes for each visit.

A newer method is accelerated partial breast irradiation. This method targets radiation at the breast area that contained the tumor, rather than the entire breast. It’s also given in fewer, higher doses than standard external beam radiation therapy.

Radiation therapy is painless. You may feel some discomfort from lying in the required position, but this is generally short-lived.

After the session, you’re free to go about your regular activities. Generally no special precautions are needed.

In some cases, once the main radiation therapy sessions have been completed, your doctor may recommend a boost treatment to the tumor bed to further reduce the risk of recurrence. A radiation boost may involve more external radiation therapy sessions or internal radiation therapy.

Internal radiation

For internal radiation, the radioactive seeds are inserted twice a day for a few minutes in the implanted radiation device. This is usually done on an outpatient basis, and you can leave between sessions.

After the course of treatment is over, the device is removed. Usually you’re given pain medication before the holders are removed. The area may be sore or tender for a few months.


After you complete radiation therapy, your radiation oncologist will schedule follow-up visits to monitor your progress, look for late side effects and check for signs of recurrence. You’ll need less frequent follow-up visits the longer you’re cancer-free, but you’re likely to see your medical oncologist for the rest of your life.

When your radiation therapy is completed, tell your doctor or nurse if you experience:

  • Persistent pain
  • New lumps, bruises, rashes, swelling or bleeding
  • Persistent digestive complaints such as appetite changes, nausea, vomiting, diarrhea or constipation
  • Unexplained weight loss
  • A fever or cough that doesn’t go away
  • Any other bothersome symptoms

Is Radiation Therapy A Better Breast Cancer Treatment?  was originally published on

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