External Radiation Therapy

During this procedure, high-energy x-rays are aimed at the breast and sometimes at nearby areas that still contain some lymph nodes, such as under the arm (if only a "sampling" was done), above the collarbone, and along the breastbone. The goal of radiation therapy is to destroy any cancer cells that may still remain in the breast or surrounding lymph node areas.

These high-energy x-rays are delivered by a linear accelerator or a cobalt machine. The difference between the two machines is simply that the beams are produced by different energy sources.

Often, a patient's first visit to the radiation department takes 1 to 2 hours and doesn't involve any treatments. You will probably talk with the radiation therapist, a physician with special training in the use of radiation, who will review your records and decide the best way to proceed with your treatment.

You will probably also meet the technician who delivers the treatment, and the radiation therapy nurse, who works closely with the doctor and can answer any questions you have about treatment, potential side effects, and what you can do about them.

During the first visit, ink lines or small tattoo marks will be drawn on your skin around the treatment area to mark exactly where to aim the radiation. The marks are generally made with permanent ink, and you should not attempt to wash them off until treatment is completed. These marks ensure that the area treated is the same every day. Many women wear old under-clothes during treatment because the marking may stain clothing.

The radiation therapist will consult with the dosimetrist, who computes the dosages of radiation. The standard treatment for early stage breast cancer is almost always 4,400 to 5,000 rads (radiation absorbed dose). A rad refers to the amount of radiation that is absorbed by the breast tissue.

Your actual number of treatments will depend on the total dose you need. Usually, treatments are given 5 days a week, Monday through Friday, for about 5 weeks. To protect normal tissue, it is better to give a little radiation each day than to give a lot of radiation all at once. A single treatment takes about 20 to 25 minutes. Only a few minutes of this time are of exposure to radiation; most of the time is spent putting the patient in position. Most people continue to work or pursue other activities throughout the treatment period.

It is very important to have all your treatments. However, if you have to miss a treatment, it can be made up. If you do not finish the full course, you may not have gotten enough radiation to destroy the cancer cells.

For more information about what to expect during radiation therapy, contact the National Cancer Institute for a copy of Radiation Therapy and You: A Guide to Self-Help During Treatment.