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Radiation Therapy

Radiation therapy (sometimes called radiotherapy) is one of the main methods of breast cancer treatment. It uses a high energy beam to destroy cancer cellsCell:
The basic structural and functional unit of all organisms.
. It works by damaging the DNADNA:
Short for Deoxyribonucleic acid. DNA is found in the cells of our bodies. It contains the genetic instructions used in the development and functioning of all known living organisms and some viruses. Your DNA contains genetic information that is unique to you.
of cancer cells so that they can’t continue to grow. Radiation is a local treatmentLocal treatment:
A treatment method that is applied to and takes effect only in the area of the body where it is applied. Surgery and radiation therapy are local treatments for breast cancer.
because it is applied and takes effect in a specific part of the body (where the tumourTumour:
An abnormal mass of tissue that occurs when cells divide more than they should or do not die when they should. Tumours may be benign (not cancer) or malignant (cancer). A tumour is also called a neoplasm.
is located).

Radiation therapyRadiation therapy (Sometimes called radiotherapy):
A treatment method that uses a high energy beam to destroy cancer cells by damaging the DNA of cancer cells so that they can’t continue to grow.
is usually given after breast cancer surgery. The goal of radiation therapy is to destroy any cancer cells that might remain in the breast area after surgery. Radiation also helps reduce the risk of recurrenceRecurrence:
Cancer that returns after treatment.
(the cancer coming back). Radiation treatments will not begin until several weeks after you have had your surgery to give the area time to heal. If you are also having ChemotherapyChemotherapy:
A treatment method that uses medication to destroy cancer cells.
, that will usually occur first and radiation therapy will be delayed until your chemotherapy treatment is complete. A radiation oncologistOncologist:
A doctor or surgeon who specializes in treating cancer. A medical oncologist specializes in drug therapy (chemotherapy) for cancer. A radiation oncologist specializes in treating cancer with radiation.
will be involved in planning your radiation treatments.

For very large breast cancer tumours, radiation therapy may be given before surgery. The goal of radiation therapy before surgery is to shrink the tumour so that it is easier to operate on.

Types of Radiation Therapy

External beam radiation therapy is the most common type of radiation therapy and uses a large x-ray machine called a linear accelerator, or LINAC. At the start of your therapy, the radiation team will do a CT scanComputed Tomography (CT) scan:
An imaging technique that takes a series of x-rays from many different angles and combines them to create a detailed 3-dimensional image of the bones and tissues in your body, such as the breast.
to get an exact image of your body and internal organs, including the lungs and the heart. This will help them plan your treatment, including the dose of radiation you will receive, so that any damage to these organs and your skin is as small as possible. The team will also make small, tattoo-like marks on your skin. These marks are about the size of a freckle and may or may not be permanent. They allow the team to direct the radiation exactly where it is needed each time you receive radiation therapy.

Typically you will receive 1 session every day, 5 days a week, for a period of 3 to 6 weeks. Radiation therapy is usually an outpatient procedure, and you will not need to stay overnight in hospital. It is not recommended to wear any lotions, powders, deodorants or antiperspirants on the day of your treatment, as they can interfere with how your skin tolerates the radiation therapy. The process of having radiation treatment is not very different from having an x-ray. A radiation therapistRadiation therapist:
A licensed health care provider who gives radiation therapy to cancer patients.
will help you to get onto a treatment table and into the correct position to receive your treatment. The radiation machine may seem big and noisy, but it will not touch you during your treatment.

Once you are in the correct position, it is important that you stay still. The radiation therapist will then leave the room and go to a control room from where they can administer the radiation beam. They will come in and out to re-position you and the radiation machine as needed so that the beam can be aimed at the breast cancer tumour from different angles. Although the therapist won’t be in the room when the radiation beam is applied, they can see and hear you and you are not alone. If you feel sick or have any concerns, don’t be afraid to tell them. They can stop the radiation treatment and come to assist you. Usually each session lasts only a few minutes and you shouldn’t feel any pain during the treatment session.

Internal radiation therapy, also called brachytherapy, is also based on the use of radiation to kill cancer cells. BrachytherapyBrachytherapy:
A type of radiation therapy where only a small amount of breast tissue receives radiation treatment in the form of small radioactive pellets or ‘seeds’ that are placed within the breast next to the tumour. Depending on the type of brachytherapy, the radiation source may or may not be permanently implanted.
is a form of treatment called ‘partial breast irradiation’. This means only a small amount of the breast tissue receives the radiation treatment. Instead of using an external beam, the radiation is applied in the form of small radioactiveRadioactive:
Describes something that gives off radiation. Radiation is energy released in the form of particle or electromagnetic waves. Common sources of radiation include radon gas and medical X-rays.
pellets or ‘seeds’ that are placed within the breast next to the tumour. Whether brachytherapy is an option for you will depend on the size and location of the tumor, among other factors.

There are two main types of brachytherapy, depending on whether or not the radiation source is permanently implanted into the breast.

When the radiation source is not permanently implanted, the brachytherapy technique requires several hollow tubes (called catheterCatheter:
A flexible tube that is inserted into the body in order to remove or deliver a substance to the body, or to keep a passageway open.
), or a single inflatable balloon to be inserted into the area being treated and left in place. These catheters are removed after the last treatment. During each treatment, radioactive pellets are placed through the tubes for a few minutes and then removed, twice a day for 5 days.

If the radiation source is permanently implanted, the radiation pellets are inserted inside the breast and left in permanently. This procedure takes approximately 1 hour and is done in the hospital under light sedation. You will not need to stay at the hospital overnight. 

One advantage of brachytherapy is that the remaining breast tissue keeps its normal texture after the radiation treatment and the side effects are limited to the area of the breast where surgery was done.

Not everyone diagnosed with breast cancer who requires radiation therapy will be able to have brachytherapy.  Based on all of the information available about the breast cancer, your radiation oncologist will discuss the options available to you. For those who are eligible to have brachytherapy, some choose to have this procedure over external beam radiation therapy because the treatment time is shorter (though more invasive).

Limiting radiation exposure 

Different tissues in the body can tolerate different amounts of radiation. A person’s total exposure to radiation must be limited during treatment and over time. Once you receive the maximum dose of radiation therapy to an area, such as the affected breast or the chest wall, the area may not be able to tolerate more radiation. For this reason, if you have had radiation therapy to the breast in the past, it may not be recommended again in the future.

Radiation therapy is also not recommended for pregnant women because of health risks to the developing baby. If you need to have radiation therapy while you are pregnant, your radiation oncologist and an expert medical physicist will work together to minimize those risks. It is extremely important that you inform your radiation oncologist if there is any possibility you may be pregnant, and avoid becoming pregnant during the treatment period.

Side effects

You may experience side effects during radiation therapy, because the radiation can harm healthy cells as well as cancer cells. The dose of radiation is carefully monitored to have the most impact on the cancer while doing the least harm to healthy cells.

The most frequent side effects of radiation therapy are due to temporary and reversible damage to the skin and include skin redness, sunburn-like skin changes, swelling, and fatigue. These side effects should go away within a few weeks to a few months after the treatment is complete. In the long term, it is possible that scar tissue can develop at the radiation site, which may affect breast reconstruction or lead to problems with breast feeding later on.

Tips for preventing and managing skin irritation with radiation treatment:

  • Wear loose-fitting cotton shirts

  • Avoid using harsh soaps and skin care products on your breasts. Use fragrance-free, gentle, moisturizing products

  • Avoid letting the skin on your breasts come into direct contact with sunlight. It is also recommended to use a sunscreen with an SPF of at least 50 on the treated skin for at least 2 years after the end of radiation treatment

  • Wear a supportive bra without an underwire that keeps your breasts separated and lifted. The skin can be more prone to irritation where skin meets skin, (e.g., skin folds). If you have large breasts and go without a bra, try inserting a soft piece of cotton fabric in the crease under your breasts

  • If there are raw areas of skin from the radiation treatment, you may wish to avoid wearing a bra

  • Using cornstarch in areas around the breast with skin folds (under and between the breasts, and in the arm pits) can help absorb moisture and keep the breasts dry. This helps because a build-up of moisture can increase skin irritation and the risk of yeast infections

  • If you experience pain or significant discomfort, speak to your radiation oncologist or health care team about options for managing the side effects

Ask your health care team about the benefits, limitations and possible side effects of radiation therapy to help you make an informed decision about your treatment.


American Cancer Society. Radiation Therapy for Breast Cancer. Accessed January 9, 2014.

Breastcancer.org. Radiation Therapy. Accessed January 9, 2014.

Cleveland Clinic. Radiation Therapy for Breast Cancer. Accessed January 9, 2014.

National Cancer Institute. External Beam Radiation Therapy. Accessed January 9, 2014.

Smith, G.L., Xu, Y., Buchholz, T.A., Giordano, S.H., Jiang, J., Shih, Y.C.T., & Smith, B.D. (2012). Association Between Treatment With Brachytherapy vs. Whole-Breast Irradiation and Subsequent Mastectomy, Complications, and Survival Among Older Women With Invasive Breast Cancer. JAMA; 307 (17): 1827-1837.