Radiation therapy commonly is used after lumpectomy to treat early-stage breast cancer and reduce the risk of the cancer coming back (recurrence). Brachytherapy is a newer form of radiation therapy and an alternative to traditional whole-breast external beam radiation therapy. Brachytherapy delivers a higher dose of radiation to a smaller area of the breast over a shorter period of time compared to traditional (external beam) radiation therapy. Doctors sometimes refer to brachytherapy as accelerated partial breast irradiation (APBI). In the United States, brachytherapy use has been increasing steadily since it was first approved by the U.S. Food and Drug Administration in 2002.
A large study has found that many women who were treated with brachytherapy were not good candidates for that form of radiation therapy based on the characteristics of the breast cancer with which they were diagnosed. These women may have been better treated with traditional whole breast radiation instead.
The results were published in the Dec. 16, 2011 online edition of the Journal of the National Cancer Institute.
Traditional external beam radiation therapy aims cancer-destroying energy at the whole breast or to the area of the breast where the cancer was. The source of the radiation is outside the breast, which is why it's called "external beam." Many studies have shown the long- and short-term effectiveness of external beam radiation therapy. The drawbacks of traditional radiation therapy include daily trips to the hospital for treatments -- typically 5 days a week for 4 to 6 weeks. Traditional radiation therapy also has a large field and may expose healthy tissue, such as the heart and lungs, to radiation.
To overcome the drawbacks of traditional radiation therapy, doctors have developed different ways to deliver radiation. Brachytherapy places the radiation source inside the breast. Two types of brachytherapy are used right now and another is experimental. They are:
- Multi-catheter internal radiation, also called interstitial needle-catheter brachytherapy. This approach uses radioactive "seeds" to deliver radiation directly to the area where the cancer was. The seeds are placed in very small tubes (catheters) that are stitched into place under the skin. The seeds are left in the tubes for a few hours or a few days. You remain in the hospital during treatment. Once the treatment is completed, the seeds, tubes, and stitches are removed and you go home.
- Balloon internal radiation, known by the brand name MammoSite. This approach places a special tube with a balloon on one end in the breast where the cancer was. The tube comes out of the skin through a small hole. The tube and balloon are placed either during lumpectomy or afterward in a surgeon's office. During each treatment, a machine places a radioactive seed into the center of the balloon for 5 to 10 minutes -- just long enough to deliver the required dose of radiation. After the seed is removed, you may leave the treatment center. A total of 10 treatments are usually given over 5 days. That means two treatments per day, about 6 hours apart. When the final treatment is done, the balloon and tube are removed through the small hole in the skin.
- 3-D conformal external beam radiation (3DCRT). This experimental approach starts with a planning session (simulation). A special MRI or CAT scan of the breast is done and is used to map out small treatment fields for the area at risk. The type and distribution of radiation is designed to maximize the dose to the area that needs to be treated and avoid or minimize radiation to tissue near the area. The radiation is delivered with a linear accelerator, the same machine used in traditional external radiation, twice a day for 1 week.
In 2009 a panel of experts from the American Society for Radiation Oncology (ASTRO) developed guidelines to help doctors decide which women are good candidates for brachytherapy. The ASTRO brachytherapy guidelines classify patients into one of three groups:
ASTRO brachytherapy classification is based on a number of cancer characteristics, including:
- cancer size: the larger the cancer, the more unsuitable brachytherapy is
- cancer type: lobular cancers are less suitable for brachytherapy than ductal cancers
- cancer hormone receptor status: hormone-receptor-negative cancers are less suitable for brachytherapy
- cancer in the blood vessels, lymph channels, and lymph nodes: cancers that involve blood vessels or lymph tissue are less suitable for brachytherapy
- number of breast tumors: cancers with multiple clusters or tumors of cancer cells in different locations in the breast (multi-focal) are less suitable for brachytherapy
Researchers looked at the medical records of nearly 139,000 women treated with radiation therapy after surgery for early-stage breast cancer. The records were in a national health database called SEER (Surveillance, Epidemiology, and End Results). All the women were treated sometime between 2000 and 2007, before the ASTRO brachytherapy guidelines were released in 2009.
About 2.6% of the women got brachytherapy. The brachytherapy suitability of each of these women was classified using the 2009 ASTRO guidelines.
For the women who got brachytherapy, the researchers found:
- 66% were classified as either "cautionary" or "unsuitable" for brachytherapy
- only 34% were classified as "suitable"
Even though the women in the study were treated with brachytherapy before the ASTRO guidelines were developed, the results suggest that many women unsuitable for brachytherapy are getting brachytherapy. This possibility is more of a concern because brachytherapy use has continued to increase since 2007 when the last of the patients in this study were treated.
Findings from another large study suggest that brachytherapy may not be as effective as whole-breast radiation therapy at reducing recurrence risk. Women in that study who got brachytherapy after lumpectomy for early-stage breast cancer were nearly twice as likely to later have a mastectomy because of cancer recurrence compared to women who got traditional whole-breast radiation therapy. That study also found that treatment complications -- such as rib fracture, breakdown of fat in the breast (fat necrosis), breast pain, and inflammation in the lungs -- were more likely among women treated with brachytherapy. Some of these higher complication rates may be because brachytherapy requires a device to be implanted under the skin.
Besides being a quicker way to deliver radiation therapy, many doctors like brachytherapy because the radiation delivery is focused, potentially avoiding exposing healthy tissue to radiation. Even though brachytherapy is becoming more popular, experts continue to warn that right now there's not enough evidence to confidently conclude that brachytherapy is as effective and safe as traditional whole-breast radiation therapy.
The studies discussed here suggest that this caution makes sense. Still, some experts feel that the results reflect early use of brachytherapy and that doctors are now better at using brachytherapy more effectively and safely. Several very large, well-designed studies are currently being done to evaluate the short-term and long-term effectiveness and safety of brachytherapy compared to traditional whole-breast radiation therapy. It will be several years before the results are available.
If you've been diagnosed with early-stage breast cancer, are having lumpectomy, and will be receiving radiation therapy after surgery, you and your doctor may consider brachytherapy as an alternative to traditional external beam radiation therapy. Perhaps the daily trips to the treatment center would be a burden because of distance. Talk to your doctors about their experience with brachytherapy compared to traditional radiation therapy. You also may want to ask about their familiarity with the technical aspects of delivering brachytherapy since placement of the catheters or balloon is a skill that can take some time to master. It also makes sense to ask about your suitability for brachytherapy based on the 2009 ASTRO guidelines.
The Breastcancer.org Radiation Therapy section has more information on both traditional external beam radiation therapy and brachytherapy.