Researchers are studying internal radiation, sometimes called partial-breast radiation or brachytherapy, for use after lumpectomy to see how the benefits compare to the current standard of external radiation to the whole breast. Internal radiation methods typically use small pieces of radioactive material, called seeds, which are placed in the area around where the cancer was. The seeds emit radiation into the surrounding tissue. The area that's very close to the site of the original cancer is the area that is at highest risk of recurrence.
Internal radiation is most commonly delivered using multiple small tubes or catheters, or using a balloon-catheter device called MammoSite.
- In multi-catheter internal radiation, tiny tubes (catheters) are sewn under the skin in the area where the cancer was. The ends of the tubes stick out through little holes in the skin. Tiny stitches hold the tubes in place.
The doctor or a machine places radioactive seeds into the tubes just long enough to deliver the prescribed dose. If low-dose radiation seeds are used, the treatment can take a few days. During treatment, you stay in the hospital because there is radioactivity inside you. Special precautions are taken to keep you and those around you safe from the radiation. Once the treatment is done, the radioactive seeds, stitches, and tubes are removed. Then you can go home.
If high-dose radioactive seeds are used, each seed might be left in for up to 10 minutes. The seeds are then removed and you are free to leave the treatment center. You do not remain radioactive after the seeds are removed. Once the course of treatment is done, the tubes are removed. The course of internal radiation treatment is usually 1 week (5 days), with 2 treatments each day.
- In balloon-catheter internal radiation (the MammoSite system), a special tube with a balloon on the end is used. With careful planning, the balloon is placed into the area where the cancer was. The tube comes out through a little hole in the skin. The balloon is filled with fluid to hold the balloon and tube snugly in place. The MammoSite can be inserted in an operating room or in a surgeon's office and stays in place about a week and a half.
During each treatment, a machine places a radioactive seed into the center of the balloon for about 5 to 10 minutes — just long enough to deliver the prescribed dose of radiation. A total of 10 treatments are usually given over 5 days. That means 2 treatments per day, about 6 hours apart. When the final treatment is done, the balloon is removed through the small hole in the skin.
Internal radiation boost
Internal radiation can be used for giving a boost dose at the end of an external radiation treatment regimen. A boost dose is a supplemental dose of radiation given towards the end of your treatment to target the area around where the tumor was. The boost dose is given in the same manner as regular internal radiation, using either small tubes or a balloon-catheter, and radioactive seeds. The boost dose will be calculated such that you’ll get a slightly higher amount of radiation each day than you did for the first few weeks of your regimen.
Benefits and drawbacks of internal radiation
Internal radiation was developed to reduce risk of recurrence while shortening the amount of time it takes to get radiation treatment. Internal radiation also limits the dose of radiation (and associated side effects) to surrounding normal tissue. Internal radiation also MAY be able to be given again — but only to another part of the breast — if a new breast cancer is diagnosed in the future. External, whole-breast radiation usually can't be given again to the same breast.
Compared to external radiation, internal radiation has several benefits:
- The treatment time is shorter — 1 week versus up to 7 with external radiation. Intraoperative internal radiation has an even shorter treatment time because it's done during surgery.
- Radiation is given only to the area where the cancer is most likely to come back. Less of your body receives radiation, so there may be fewer side effects.
- The preliminary results from the small number of studies done so far show a very low risk of recurrence after internal radiation.
But there are some unknowns involved with internal radiation that should be discussed with your doctor as you make your treatment decisions:
- Internal radiation has no long-term track record. This means that the benefits and side effects of internal radiation aren't completely understood. The benefits and side effects of external, whole-breast radiation have been studied for more than 30 years in thousands of people. Talk to your doctor about how to make a decision between a new approach and an established approach.
- Most internal radiation techniques require extra training and experience. Doctors have to know how to select appropriate people for the treatment and how to properly deliver the radiation.
The early results from the first small studies on internal radiation look very promising. If you are very interested in internal radiation, the NSABP B-39 clinical trial is comparing internal radiation to external, whole-breast radiation. Ask your doctor about participating, or find out more on clinical trials.