In the study reviewed here, women who got internal partial-breast irradiation with the MammoSite system, also known as brachytherapy, had the same outcomes as women who got traditional external radiation therapy in the 3 to 4 years after lumpectomy to treat early-stage breast cancer.
The results were presented at the 2008 American Society for Therapeutic Radiology and Oncology (ASTRO) meeting.
Radiation therapy is used after lumpectomy to destroy any cancer cells that may be left behind and to reduce the risk of the cancer coming back. There are two main types of radiation.
External radiation, sometimes called external beam radiation, is the most common type of radiation. In this technique, a large machine called a linear accelerator aims a beam of high-energy radiation at the area affected by the cancer. This form of radiation is given on an outpatient basis 5 days a week, over 5 to 7 weeks, depending on the particular situation.
Internal radiation, or brachytherapy, typically uses 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. Brachytherapy usually is given over 5 to 7 days, a much shorter time than external radiation. Still, brachytherapy systems require a skilled and experienced medical team and available radioactive materials.
In the MammoSite system, a catheter with a balloon on the end is placed in the area where the lumpectomy was done. The balloon-catheter device can be placed during lumpectomy surgery or in a surgeon's office soon after the lumpectomy. The end of the catheter pokes out through a small hole in the skin. The balloon is filled with fluid to hold the device snugly in place.
MammoSite brachytherapy radiation is usually given two times per day for 5 days. The women in this study followed this schedule. During each treatment, a machine places a radioactive seed into center of the balloon for up to 10 minutes. The seed is then removed. Women receiving brachytherapy can leave the treatment center between treatments -- they're not radioactive after the seed is removed. When the final treatment is done, the balloon is drained and removed through the hole in the skin.
More than 1,400 women who got MammoSite radiation from 2002 to 2004 were followed in this study. The results:
After 4 years, more than 94% of the women were alive and almost 90% were alive without the cancer coming back or being diagnosed with a new breast cancer.
More research with longer follow-up time will help doctors better understand which women will benefit the most from the MammoSite system. Some women may choose to have mastectomy instead of lumpectomy because it's too hard for them to get 5 to 7 weeks of daily radiation therapy after surgery. MammoSite and other brachytherapy systems can deliver radiation therapy in only 5 days. This may allow more women to choose lumpectomy over mastectomy.
If radiation therapy will be part of your treatment plan after surgery, you and your doctor will talk about which surgery and which radiation therapy technique makes the most sense for you. For some women, external radiation is the best approach. For others, internal partial-breast radiation therapy may be a good option. The Breastcancer.org Radiation Therapy section offers more information, including how radiation works to treat breast cancer, the different approaches to delivering radiation, and what to expect during and after treatment.
BOSTON, Sept. 22 (MedPage Today) -- For women with early stage breast cancer, a week of balloon brachytherapy is as effective as standard whole-breast radiation in preventing recurrence, a researcher said here.
Analysis of data from a registry database showed a four-year recurrence rate of 2.65% for women treated with partial breast irradiation using the MammoSite radiation therapy system, according to Peter Beitsch, M.D., of Medical City Dallas Hospital in Dallas.
That's comparable to the recurrence rate among historical controls treated with standard external beam radiation, he told attendees at the American Society for Therapeutic Radiology and Oncology meeting.
The finding may "actually increase the rate of breast conservation," he said, because standard radiation treatment after lumpectomy -- usually a course of several weeks -- can be impossible for some women.
For those unable or unwilling to commute to a cancer center for several weeks, he said, mastectomy may be the preferred option. "Now they can stay for a week and save their breast," he said.
The procedure -- accelerated partial breast irradiation using the MammoSite system -- has been performed for more than five years, Dr. Beitsch said, and the registry has data from 1,440 women with 1,449 primary early stage breast cancers between May 2002 and September 2004.
With a median follow-up of 36 months for the whole group, there were 28 ipsilateral breast tumor recurrences (2.15%) as well as three axillary recurrences, 11 contralateral new primaries, and 16 distant failures.
For the first 400 consecutive cases, median follow-up was 44 months. In that group, there were eight ipsilateral recurrences (2.65%), as well as one axillary recurrence, six distant failures, and two contralateral new primaries.
Overall, four-year actuarial survival was 93.9% with a disease-free survival of 88.9% and cancer-specific survival of 100%, Dr. Beitsch reported.
"There's a lot of angst about partial breast irradiation," he said. "Everybody was concerned that we're only treating part of the breast (and) recurrences are going to be ridiculous."
Although comparison with standard treatment is difficult, Dr. Beitsch said, balloon brachytherapy "certainly isn't markedly worse."
"Everyone is intrigued by balloon brachytherapy," said Anthony Zietman, M.D., of Harvard and Massachusetts General Hospital, who was not involved in the study.
"We have three or four years of follow-up (and) we need a little bit more before there's complete confidence," Dr. Zietman said. "We need to know exactly who is best served by balloon brachytherapy and who is under-served by that therapy," he said.
If the alternative were losing a breast, he added, he would consider the MammoSite procedure, but when making those decisions physicians have to "consider the limitations of the data."
The MammoSite registry is sponsored by Hologic of Bedford, Mass.
Dr. Beitsch said he had no conflicts.
Primary source: International Journal of Radiation Oncology - Biology - Physics Source reference: Beitsch PD, et al "Recurrence and Survival in the American Society of Breast Surgeons (ASBS) MammoSite-RTS Registry Trial" Int J Radiat Oncol Biol Phys 2008; 72(1 Suppl): Abstract 5.
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