MammoSite RTS: Broadening Access to Breast Conservation Therapy
An estimated 257,800 new cases of breast cancer are expected to occur among women in the United States during 2002, with about eighty one percent of patients diagnosed when the disease is still in its early stage. Many early stage patients still choose to have a mastectomy, but a growing number are opting for a less invasive course of treatment. This approach, called breast conservation therapy (BCT), usually involves tumor excision via lumpectomy, followed by radiation therapy to reduce the likelihood of recurrence.
Although breast conservation therapy allows a woman to save her breast, 50 percent of patients with early stage breast cancer still choose to have a mastectomy, despite comparable long-term recurrence and survival rates. According to a National Cancer Institute study, an estimated 25 percent of lumpectomy patients don’t receive any follow-up radiation treatment, with the chances of forgoing this therapy increasing the farther away a woman lives from a radiation treatment center.
Proxima Therapeutics has developed a device that is used to internally administer a site-specific, prescribed dose of radiation during a five-day course of therapy. The U.S. Food and Drug Administration (FDA) recently cleared this device, called the MammoSite Radiation Therapy Systems (RTS). MammoSite expands the range and flexibility of post-surgical treatment options for breast conservation therapy. Because of the less-invasive nature and short duration of the treatment, MammoSite could make it easier for more women to consider the choice of lumpectomy and provides physicians with an important new tool for the practice of breast conservation therapy.
The MammoSite RTS internally delivers radiation directly to the tissue surrounding the original tumor, minimizing radiation exposure to the rest of the breast, skin, ribs, lungs and heart. During the lumpectomy procedure or shortly thereafter, the deflated MammoSite balloon is placed inside the tumor resection cavity. The applicator shaft, a tube connected to the balloon, remains outside the breast. Once in place, the balloon is inflated with saline to fill the cavity, the catheter site is dressed, and the patient may go home. The balloon remains inflated for the entire time that the patient is receiving radiation therapy. The patient returns to the hospital for treatment on an outpatient basis where a radioactive “seed” is inserted within the inflated balloon, beginning a one to five day sequence of treatments. No source of radiation remains in the patient’s body between treatments or after the final procedure. When the therapy is concluded, the balloon is deflated and the MammoSite RTS catheter is easily removed.
The MammoSite RTS is in the category of radiation therapy known as brachytherapy. Brachytherapy for the treatment of prostate cancer has become well established, but MammoSite represents a novel application of this approach for women with breast cancer. Although similar to the MammoSite RTS, conventional brachytherapy has not been widely accepted for breast conservation therapy due to its invasiveness and complexity. Conventional brachytherapy requires the insertion of 14 to 20 catheters per procedure, and both placement and dosage calculations are complex. With its single catheter approach, the MammoSite procedure is far less invasive for the patient and relatively simple for the physician to perform.
The MammoSite RTS was cleared for use by the U.S. Food and Drug Administration (FDA) on May 6, 2002 and is now becoming available in many markets throughout the country. Internally administered radiation therapy is covered by most insurers. Specific coverage for the MammoSite RTS will depend on a patient’s individual health care plan. For up-to-date information regarding geographic availability of the MammoSite RTS, please visit
www.mammosite.com or call 1-86-MammoSite (1-866-266-6748).