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 call brachytherapy accelerated partial-breast irradiation (APBI).
Brachytherapy use increased steadily in the United States since it was first approved by the U.S. Food and Drug Administration in 2002. But since 2008, using brachytherapy after lumpectomy has slightly declined. Many experts were concerned about the increase because there haven’t been many long-term studies showing that brachytherapy works as well as traditional radiation therapy.
One of the largest studies done so far on the outcomes of brachytherapy suggests that brachytherapy after lumpectomy results in survival rates and recurrence rates that are similar to whole-breast radiation.
The research was published online on April 28, 2015 by the Annals of Surgical Oncology. Read the abstract of “Outcomes of Breast Cancer Patients Treated with Accelerated Partial Breast Irradiation Via Multicatheter Interstitial Brachytherapy: The Pooled Registry of Multicatheter Interstitial Sites (PROMIS) Experience."
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.
To see if brachytherapy offered the same survival and recurrence outcomes as traditional whole-breast radiation, the researchers looked at the records of 1,131 women who had lumpectomy followed by 5 days of multi-catheter internal radiation. The women were treated from 1992 to 2013 and they ranged in age from 22 to 90. The characteristics of the breast cancers the women were diagnosed with were:
- about 75% of the women were diagnosed with invasive ductal carcinoma
- about 20% were diagnosed with DCIS
- most of the women were diagnosed with early-stage disease
- 83% of the cancers were estrogen-receptor-positive
- 70% of the cancers were progesterone-receptor-positive
- 6% of the cancers were HER2-positive
Half the women were followed for less than 7 years and half the women were followed for longer than 7 years.
The 10-year outcomes were:
- 96% of the women were alive
- the risk of breast cancer coming back in the same breast was 7.6%
- the risk of cancer coming back in the opposite breast was 4.6%
- the risk of breast cancer coming back in the chest wall, lymph nodes, or breast skin (regional recurrence) was 2.3%
- the risk of breast cancer coming back in an area of the body away from the breast such as the bones or liver (metastatic recurrence) was 3.8%
These outcomes are similar to results in women treated with whole-breast radiation after lumpectomy.
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. While the results of this study are promising, other 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, though more study results are expected to be published relatively soon.
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.
The Breastcancer.org Radiation Therapy section has more information on both traditional external beam radiation therapy and brachytherapy.