Overview

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

The X-rays or particles are painless and invisible. You are not radioactive after treatment, so it is safe to be around other people, including children.

Radiation therapy for breast cancer may be delivered through:

• External radiation. A machine delivers radiation from outside your body to the breast. This is the most common type of radiation therapy used for breast cancer.
• Internal radiation (brachytherapy). After you have surgery to remove the cancer, your doctor temporarily places a radiation-delivery device in your breast in the area where the cancer once was. A radioactive source is placed into the device for short periods of time over the course of your treatment.

Radiation therapy may be used to treat breast cancer at almost every stage. Radiation therapy is an effective way to reduce your risk of breast cancer recurring after surgery. In addition, it is commonly used to ease the symptoms caused by cancer that has spread to other parts of the body (metastatic breast cancer).