Effectiveness of Radioactive Seed Localization for Pinpointing Breast Tumors

An ongoing study comparing the use of radioactive seed versus wire localization for pinpointing tumors during breast cancer surgery is being conducted by Richard J. Gray, M.D., and Barbara A. Pockaj, M.D., surgeons at Mayo Clinic in Arizona (www.mayoclinic.org) . The study has completed recruitment of 400 patients and has been expanded to include Mayo Clinic locations in Rochester, Minn., and Jacksonville, Fla.

Radioactive seed localization involves implanting radioactive pellets the size of a grain of rice into the affected area of the breast. Surgeons then pinpoint the tumor using a hand-held Geiger counter. This procedure guides the surgeon to the precise location to make the incision so the cancer and radioactive seed can be removed.

The alternative to radioactive seed localization is wire localization, a procedure where a cumbersome guide wire is inserted into the breast, which is less comfortable for the patient and may not allow for the same precision in surgical margins. Radioactive seed localization can be done up to five days prior to surgery, whereas the guide wire must be placed the same day as surgery.

Results of the study will be presented at the spring 2006 meeting of the American Society of Breast Surgeons. Preliminary results on the first 100 patients (all at Mayo Clinic in Arizona) demonstrate that radioactive seed localization was (1) considered more convenient by patients; (2) resulted in lower rates of positive margins in the first specimen and at the end of the operation; and (3) resulted in fewer patients needing re-operation for positive margins (62% relative improvement in the rate of re-operation for positive margins). Overall, the preliminary results show that radioactive seed localization is a more precise, less invasive approach than wire localization and that it helps women achieve breast conservation in a single operation.

"Most importantly, this technology allows us to be more precise when operating for breast cancer, while providing a more convenient process for the patient," says Rick Gray, M.D., surgical oncologist at Mayo Clinic.

The amount of radiation given off by the radioactive seed is less than the amount emitted from a standard X-Ray. Randomized studies published in the Annals of Surgical Oncology have shown that adequate surgical margins are achieved twice as often with radioactive seed localization as compared to wire localization. This translates to a higher likelihood that all cancer will be removed from the breast in the initial operation in the case of a lumpectomy.

Mayo Clinic has been conducting clinical trials of radioactive seed localization since 2002 in Arizona. Radioactive seed localization is currently under review for approval by the Food and Drug Administration.

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Mayo Clinic Cancer Center is one of only 39 U.S. medical centers that have been named as a National Cancer Institute (NCI) Comprehensive Cancer Center. To receive this designation, an institution must meet rigorous standards demonstrating clinical excellence in treating cancer patients and scientific excellence in its research programs. Mayo Clinic Cancer Center is ranked by the NCI as one of the top 10 cancer centers in the nation, and is the only national, multi-site center with the NCI's Comprehensive Cancer Center designation. In Arizona, Mayo's clinical and research experts work together to address the complex needs of cancer patients, with a dedication to understanding the biology of cancer; discovering new ways to predict, prevent, diagnose and treat cancer; and transforming the quality of life for cancer patients today and in the future.

Did you know?
An ongoing study comparing the use of radioactive seed versus wire localization for pinpointing tumors during breast cancer surgery is being conducted by Richard J. Gray, M.D., and Barbara A. Pockaj, M.D., surgeons at Mayo Clinic in Arizona (www.mayoclinic.org) . The study has completed recruitment of 400 patients and has been expanded to include Mayo Clinic locations in Rochester, Minn., and Jacksonville, Fla.