Breast Cancer Overview

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Treating Breast Cancer TOPICS

Radiation therapy for breast cancer

Radiation therapy is treatment with high-energy rays (such as x-rays) or particles to kill cancer cells. Radiation therapy may be used to kill cancer cells remaining in the breast, chest wall, or underarm area after surgery or, less often, to shrink a tumor before surgery. Radiation to the breast is often needed after breast-conserving surgery. It is usually given after any chemotherapy.

Radiation is also used to treat cancer that has spread to other areas, for example to the bones or brain. It can be given in 2 main ways.

External beam radiation

Most often, external beam radiation is used for treating breast cancer. It is much like getting a regular x-ray but for a longer time.

Treatment is usually given 5 days a week (Monday through Friday) in an outpatient center. It lasts about 5 to 6 weeks. With some newer methods, treatments may only go over a few weeks or even less time. This is called accelerated breast irradiation.

Each treatment lasts a few minutes. The treatment itself is painless. Ink marks or small tattoos may be put on your skin. These will be used as a guide to focus radiation on the right area. You might want ask your health care team if these marks will be permanent.

Possible side effects of external beam radiation: The main side effects of radiation to the breast are swelling and heaviness in the breast, sunburn-like changes in the skin over the treated area, and feeling very tired. The breast may feel hard for a time. Weakness and fracture of the ribs can also occur. Most skin changes get better within a few months. Changes to the breast tissue take longer to go away.

Radiation can lead to problems with breast reconstruction. Women who have had breast radiation may have problems breastfeeding later on. Radiation to the breast can also sometimes damage some of the nerves to the arm. This can lead to numbness, pain, and weakness in the shoulder, arm and hand. Radiation to lymph nodes under the arm can sometimes cause long-term arm swelling called lymphedema. You can get more information on lymphedema in the “Lymphedema after breast cancer treatment” section.


Another way to give radiation to the breast is to place radioactive seeds (pellets) into the breast tissue. This may be given along with external beam radiation to add an extra “boost” of radiation to the tumor in patients who have had breast conserving surgery. It is also used in some patients as the only source of radiation (instead of radiation to the whole breast). So far the results have been good, but it may not be as good as external beam radiation long-term.

There are different types of brachytherapy. The most common type used to treat breast cancer is called intracavitary brachytherapy. A device is put into the space left from breast-conserving surgery, and then a source of radiation is put in the device for a short time and then removed. Treatments are given twice a day for 5 days.

Possible side effects of brachytherapy include redness, bruising, breast pain, infection, and a breakdown of an area of fat tissue inside the breast. As with whole breast radiation, weakness and fracture of the ribs can also occur.

Last Medical Review: 09/17/2013
Last Revised: 01/31/2014