MammoSite® Shows Promise for Early-stage Breast Cancer Treatment

MammoSite® Shows Promise for Early-stage Breast Cancer Treatment

MammoSite®, a delivery system for partial breast irradiation, appears to be an effective treatment for early-stage breast cancer. These findings were recently published in the journal Cancer.

Each year breast cancer is diagnosed in more than 178,000 women in the United States alone. Early breast cancer refers to cancer that has not spread beyond the breast or lymph nodes under the arm. Cure rates for early breast cancer have steadily improved with advances in screening methods and treatments.

Treatment options for breast cancer may include surgery, radiation, chemotherapy, and hormonal therapy. In earlier stages of breast cancer, radiation is often used in combination with other treatments.

Radiation therapy uses high-energy X-rays or other types of radiation to kill the cancerous cells within the breast tissue. Radiation may be delivered through external radiation, which uses a machine to deliver the rays from outside the body toward the cancer over a period of five to seven weeks, or internal radiation therapy, which utilizes radioactive substances placed in needles, seeds, or thin tubes directly into or near the cancer; this method often requires less time.

Internal radiation therapy for breast cancer is often referred to as partial breast irradiation or brachytherapy. It may be done at the time of breast surgery or as an outpatient procedure. Once the radiation treatments are complete, the tubes are removed from the breast. Currently, partial breast irradiation is much less common than external radiation.

MammoSite is a radiation delivery system that delivers partial breast irradiation over a period of five to seven days. Each day a specific dose of radiation is placed within the implanted tube for a short period of time. The radioactive material is removed each day, allowing patient to return to normal activities.

In this recent study, researchers evaluated three years of data regarding treatment efficacy, cosmetic results, and side effects associated with the use of MammoSite. A total of 1,440 women diagnosed with early-stage breast cancer who were undergoing breast conserving therapy, rather than mastectomy, were evaluated. Each received partial breast irradiation using the MammoSite delivery system.

Of the 1,440 women, 1,255 had invasive breast cancer with an average tumor size of 10mm; 194 women had ductal carcinoma in situ (DCIS), an early form of breast cancer that develops in the lining of the milk ducts of the breast. The overall period of follow-up was 30 months.

  • 23 women (1.6%) developed a breast tumor in the opposite breast. This occurrence was slightly higher among the women who had invasive breast cancer compared with those who had DCIS (1.11% versus 59%).
  • Six of the women (0.4%) were found to have cancer that had spread to a nearby lymph node.
  • Cosmetically, the women’s breasts were in good to excellent shape following treatment and follow up at 12 and 48 months.
  • The most common side effect was breast seroma, which occurred in 23.9% of women. (A breast seroma is gathering of serous fluid in the empty space left by the tubes placed for the delivery of radiation.) These seromas were mild in most cases, producing symptoms in only 10% of the women who developed them.

The researchers concluded that MammoSite is an effective treatment option for women with some forms of early breast cancer. Results and side effects were found to be similar to other forms of partial breast irradiation techniques with similar follow up. Patients are encouraged to speak to their physician regarding their treatment options.

Reference: Vicini, F., Beitsch, P., Quiet, C., et al. Three year analysis of treatment efficacy, cosmesis, and toxicity by the American Society of Breast Surgeons MammoSite Breast Brachytherapy Registry Trial in patients treated with accelerated partial breast irradiation. Cancer. 2008. 112(4): 758-766.

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