Review of MammoSite Breast Radiation Therapy

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MammoSite breast brachytherapy is a type of accelerated breast radiation treatment. Sometimes called balloon catheter radiation, MammoSite treats breast cancer from within your breast in 5 days—with fewer side effects than the standard six- or seven-week course of external beam radiation.

Breast Radiation After Lumpectomy

Radiation may be used to treat breast cancer after your tumor has been removed with a lumpectomy. Radiation treatments are done to prevent recurrence by ensuring that any cancer cells that may remain in the tumor area are destroyed.

MammoSite radiation therapy, a type of Intracavity brachytherapy, is different than external beam radiation—it delivers radiation from inside your breast and affects only a very small portion of healthy tissue.

MammoSite Breast Brachytherapy

MammoSite was FDA approved in 2002 for post-lumpectomy breast cancer treatment. A multi-lumen balloon was then approved in 2009. The MammoSite Radiation Therapy System uses a special balloon catheter, placed in your lumpectomy cavity and inflated with saline solution. Your surgeon can place a MammoSite balloon catheter at the time of your lumpectomy, or it may be inserted at a later time.

Potential Advantages

  • MammoSite brachytherapy treatments can be completed in five to seven days, as compared to six to seven weeks of standard external radiation. This means less disruption of your schedule, less travel time, and fewer co-payments.
  • Your breast will have a surgical scar, but otherwise none of the skin burns or tissue thickening that may occur with standard radiation.
  • A very small portion of your breast will be treated by the radiation, and healthy tissue will be unaffected.
  • Standard radiation may cause fatigue, but with brachytherapy, you will be able to go about life as usual.


  • Patients say that having to avoid showers for a week is a disadvantage.
  • The sensation of having a saline-filled balloon within a breast may feel odd.
  • Infections can occur around the catheter insertion site
  • Because a catheter line will extend out of your breast while the device is in place, you'll need to wear a sports bra or a very comfortable bra to accommodate it
  • You may need to adjust your sleeping position for comfort.
  • Some research suggests that MammoSite brachytherapy may have more long-term side effects, including palpable masses and telangiectasia, than whole breast radiation therapy.

What to Expect During Treatments

MammoSite treatments are done twice a day for five consecutive days. Your treatment appointment will take about 30 minutes.

During radiation treatments, your radiation oncologist will connect your MammoSite catheter line with a radiation machine, and put a small radioactive seed through the catheter into the balloon, where it emits your radiation dose. You won't feel any heat or vibration during the treatment. At the end of each treatment session, the seed is removed and you won't carry the radiation around with you in between treatments. If any cancer cells are lingering in the tissue around your surgical margin, the radiation should kill them.

After 5 days, the balloon catheter is drained of saline and then removed through a small incision that is closed with a dressing.


You may have some side effects during or after MammoSite brachytherapy treatments. These will clear up with proper care, but make sure to go to your follow-up appointments, and let your doctor know if you have concerns about recovery.

You can expect some redness or bruising around the catheter insertion site. There may also be some pain or drainage from the scar before it heals. Take care to keep this area clean and dry. Some women may develop a skin reaction or rash.

If skin redness persists, or the area becomes puffy or looks inflamed, see your doctor right away to determine if you may have an infection.

MammoSite Has A Good Track Record

According to a 2014 study in the International Journal of Radiation Oncology, which examined over 100 women who underwent MammoSite balloon brachytherapy, results showed excellent tumor control over a median follow-up of 5.5 years.

Another 2011 study in Annals of Surgical Oncology followed nearly 200 women who underwent MammoSite accelerated partial breast irradiation (APBI) for treatment of ductal carcinoma in situ (DCIS)—after lumpectomy. It was well-tolerated and the local recurrence rate after 5 years was 3.39 percent.


MammoSite is generally for the treatment of ductal carcinoma in situ (DCIS), invasive ductal carcinoma (IDC), and a primary tumor that is 3 cm or smaller in size.

Your surgeon should be able to leave at least seven millimeters of tissue between your skin and the fully inflated balloon. Also, your lumpectomy cavity needs to be as globular as possible to accommodate the balloon; otherwise the treatment won't work properly.

In some cases, the MammoSite device must be repositioned for optimal results. Choose a surgeon who is very experienced in placing the MammoSite device, and ask if the hospital has all the proper equipment needed to implant and position the catheter.

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Article Sources

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  2. National Cancer Institute. MammoSite.

  3. Rosenkranz KM, Tsui E, McCabe EB, Gui J, Underhill K, Barth RJ Jr. Increased rates of long-term complications after MammoSite brachytherapy compared with whole breast radiation therapyJ Am Coll Surg. 2013;217(3):497–502. doi:10.1016/j.jamcollsurg.2013.03.028

  4. Cleveland Clinic. Radiation therapy for breast cancer: procedure details. Updated August 23, 2013.

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