The MammoSite Radiation Therapy System (RTS) is a device that is used to deliver radiation therapy after a woman undergoes a lumpectomy, or surgical removal of the cancerous tumor. This device delivers radiation from within the space left after the cancerous tumor is removed, to the tissue directly surrounding that cavity where tumors are most likely to recur. MammoSite reduces the course of treatment from the traditional six weeks to five days.
How does it work?
During a lumpectomy or shortly after, a single balloon catheter is inserted through a small incision into the cavity created by the surgical removal of the tumor (Figure 1). The balloon tipped end is inflated with sterile saline and contrast (for imaging) to fill the cavity. A portion of the catheter remains outside of the breast and is dressed before the patient is sent home (Figure 2).
The patient will then return to Lourdes for her daily radiation therapy treatments. Typical treatment duration is twice a day for five days (each visit to the doctor will take about an hour, with 15 minutes or less for radiation delivery). During the visit, the portion of the catheter remaining outside of the breast is attached to a computer controlled machine, called an afterloader. The afterloader is programmed to deliver a radioactive seed, attached to a wire into the balloon portion of the device where it emits radiation from within the breast (Figure 3). The patient may return home between treatments. When radiation treatment has ended, the balloon is deflated and easily removed (Figure 4).
Is the radiation exposure potentially harmful to the patient?
Because the MammoSite RTS balloon catheter delivers radiation from within, directly to the tissue surrounding the original tumor, potential exposure to the rest of the breast, skin, ribs, lungs and heart is minimized. No source of radiation remains in the patient's body between treatments or after the final procedure. Safety and performance of the device for delivery of internal radiation were proven clinically in a multi-center study, which involved women with early-stage breast cancer. The results of the study were published in the International Journal of Radiology*Biology*Physics (February 2003).
Is the MammoSite RTS similar to brachytherapy?
The MammoSite RTS is a device that delivers brachytherapy, a term applied to the process of radiating from within. Conventional breast brachytherapy has not been widely accepted by physicians and patients because of its invasiveness and complexity. Conventional brachytherapy requires the use of 15 to 30 catheters and is complex for the physician to perform. In contrast, MammoSite RTS enables treatment to be delivered with a single balloon catheter, and the procedure is relatively quick and simple to perform, with minimal discomfort to the patient.
Is treatment with the MammoSite RTS covered by health insurance?
Radiation therapy with internal radiation is an accepted treatment for breast cancer and is covered by most insurers. Specific coverage for the MammoSite RTS will depend on a patient's individual health care plan.
Can any breast cancer patient be treated with the MammoSite RTS?
No. The use of MammoSite RTS is subject to physicians' clinical judgement in consultation with their patients. To date, physicians have generally recommended MammoSite for patients 45 years of age and older with early-stage breast cancer (e.g., a tumor size of three centimeters or less and no nodal involvement).
Does treatment with MammoSite RTS cause side effects?
MammoSite RTS has been carefully tested in a clinical trial. Following the treatment, study participants experienced breast-related side effects, such as but not limited to redness, bruising and breast pain. All of these are common side effects of breast surgery and/or radiation therapy, and are usually only temporary. The MammoSite RTS has been used to treat thousands of patients, and a patient registry has been initiated to follow patients treated with MammoSite.
Ask your physician about MammoSite RTS for the treatment of Breast Cancer.