Breast cancer treatment: radiation therapy

Radiation therapy (also called radiotherapy) uses high-energy rays to kill cancer cells that may still exist after surgery. It is a local, targeted treatment.

The goal is to destroy undetectable cancer cells in a localized area, which should reduce the risk of cancer recurrence. Your treatment will be overseen by a radiation oncologist, a cancer doctor who specializes in radiation therapy.

Although radiation damages all cells in the path of its beam, the reason it’s used as treatment is because cancer cells are more easily destroyed by radiation than normal cells.

Research has shown that people who are treated with radiation after surgery are more likely to live longer and remain cancer-free longer than those who were not treated.

There are two main kinds of radiation therapy:

  • External Breast Cancer Radiation (precise delivery of high-energy beams via a large machine)
  • Internal Breast Cancer Radiation (radioactive treatments injected into the affected area)

In a lumpectomy (or partial mastectomy), surgeons remove only a portion of the breast containing the tumor, “sparing” the remainder of the breast. In a unilateral mastectomy, surgeons remove all breast tissue on the affected side; they may also remove lymph nodes under the arm (axillary lymph nodes). In a bilateral mastectomy, surgeons remove both breasts.

If radiation is included in treatment after a lumpectomy, it is almost always administered to the entire remaining breast area; this treatment is 3-6 weeks. Accelerated partial breast irradiation (APBI) targets only the area of the surgical cavity; it involves two sessions a day for five days and can be delivered with external or internal radiation.

Not all women receive radiation therapy after a mastectomy but more than half do.

Among women with early stage (I or II) breast cancer, about 3-in-5 undergo breast conserving surgery (BCS) and about 2-in-5 have a mastectomy. About 58% of these patients will undergo radiation treatment.

For women with stage III disease,  only about 1-in-5 have BCS while 7-in-10 will have a mastectomy. About 65% of these patients will undergo radiation.

About half of women with metastatic disease (stage IV) usually receive radiation and/or chemotherapy without surgery. About 11% of these patients will undergo both surgery and radiation.

From the American Cancer Society, 2016 data:

cancer treatment and survivorship

External breast cancer radiation

There are two types of external radiation used to treat cancer: traditional external beam radiation (photon therapy) and proton pencil beam scanning (PBS), a newer form of treatment. These forms of radiation are provided on an outpatient basis five days a week for a period of 5-7 weeks. [The daily routine.]

Neither form makes you radioactive!  And radiation treatments for breast cancer will not make you lose your hair. (If radiation is given to your head, that’s not the case.)

With photon based radiation, a large machine called a linear accelerator aims a beam of high-energy radiation at the area affected by the cancer. The patient is in the exact same position for each treatment.

Photons (x-rays) deposit the majority of their dose within the first inch after they hit the skin.

Because the dose from a photon beam decreases exponentially with depth, it requires higher doses to reach a tumor that lies in deeper tissue. Modern techniques such as deep inspiration breath hold (DIBH) are used to help spare the heart when treating left-side breast cancer.

Types of photon therapy include

Proton therapy is delivered by a device called a synchrotron or cyclotron. Protons deposit most of their dose at the tumor and stop traveling after they hit the tumor.

That characteristic makes proton therapy particularly beneficial when treating tumors near critical organs or structures such as the brain, heart or spinal cord. Because the proton (positively charged particles found in the nucleus of atoms) expends all its energy in the tumor, patients can receive higher doses of radiation with less damage to nearby tissue.

Proton therapy may be a good choice for breast cancer if you have

  • A need for radiation to the lymph node areas
  • Preexisting heart or lung conditions;
  • A need for treatment near your heart and lungs that puts you at risk of receiving extra radiation (left-side cancer).

There are risks to any kind of radiation. Traditional x-ray therapy can lead to side effects years or decades after treatment. Side effects can include heart and lung disease and a small risk of secondary cancers.

Proton therapy can reduce this risk by reducing radiation exposure to the heart, the lung and healthy breast tissue. In a test at Massachusetts General, reported in 2015, post-mastectomy patients who received proton therapy were “much improved in nodal coverage and cardiac sparing compared to conventional treatments by photon/electron beams.”

From ProCure (Dr. Fang is my radiation oncologist at UW/SCCA):

proton therapy


Proton therapy is currently available in only seven centers in North America.

Regardless of which form of radiation treatment you undergo, your first visit will be a simulation, a planning session. Your radiation oncologist will map out the breast area that needs treatment. In order for you to remain in the same position for each treatment session, you will be in some form of immobilization device, custom-shaped mold. Once the treatment fields are set, the radiation oncologist will mark the corners with small tattoos.

External radiation, particularly photon radiation, can irritate the skin but this is a temporary side effect.

Lymphedema is also a possible side effect of radiation treatment.

Finally, fatigue is the most common side effect of breast cancer treatment, in general.

Researchers found that exercise eased cancer-related fatigue the most. It didn’t matter if the exercise was aerobic, such as walking, jogging, dancing, hiking, etc., or anaerobic, such as weight lifting, sprinting, interval training, or jumping.

Medicines such as Provigil and Ritalin did not help cancer-related fatigue.

Internal breast cancer radiation

Researchers are studying internal radiation, sometimes called partial-breast radiation or brachytherapy, for use after a lumpectomy.  The goal is to determine benefits of this more targeted radiation with the current standard of treatment (external radiation).

Small pieces of radioactive material, called seeds, are placed in the area where the excised cancer tumor. The seeds may be delivered via tiny tubes (catheters) or inside a special tube with a balloon on its end. Technicians place a radioactive seed into the tube or balloon for about 5 to 10 minutes.

This treatment lasts five days, with two treatments per day.

Because there is no long-term track record, this form of radiation is considered experimental.

Radiation for metastatic breast cancer

From Memorial Sloan Kettering:

For women with breast cancer that has spread to other parts of the body, radiation can be used to help with symptoms in the affected area. Radiation is particularly useful for cancer that has spread to the bone and is causing pain. Radiation can help relieve pain in approximately 80 percent of women.


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