Radiation oncologists at Penn Medicine use both internal and external forms of radiation therapy to treat cancer. MammoSite, or brachytherapy, is an internal therapy in which the radiation source is placed inside the body.

Proton, IMRT, Gamma Knife® and more conventional X-ray therapies are external therapies. These treatments are delivered by machines located outside the body. Internal radiation therapy involves placing the radiation source into a small implant and placing it near the cancer site.

MammoSite is a targeted radiation therapy treatment for breast cancer performed following a lumpectomy. A small, soft balloon is placed inside the lumpectomy cavity through a small incision in the breast. A portion of the catheter remains outside of the breast and is connected to a computer-controlled machine that inserts a radiation "seed" to the area where cancer is most likely to recur.

The implant is placed in a hospital operating room by a doctor using an imaging test (such as an X-ray or MRI) to look at the exact area where the radiation needs to be to most effectively treat the cancer.

The Advantage to Patients

There are several advantages to MammoSite:

  • Shorter treatment period
  • Fewer or more mild side effects
  • Therapy is delivered on an outpatient basis

Type of Cancer Treated with MammoSite

At the Abramson Cancer Center, MammoSite is being used to treat breast cancer.