Radioactive Seed Localizations for Diagnostic Breast Cancer Lumpectomies

Radioactive Seed Localizations (RSLs) are used to localize lesions in breast tissue for surgical excision. We are the only hospital in Missoula offering this service and we have laid down the groundwork for Montana to use radioactive seeds for diagnostic purposes as opposed to seeds for therapeutic purposes. Traditionally, wire localization was the only technique available, which used an eight-inch wire with a hook to be inserted into the breast and placed next to the target the morning of surgery. There are a number of challenges with this method, which include: 

• The potential for movement during transport since the placed wire protrudes from the breast of the patient 
• Lumpectomies need to happen the same day as the wire localization which requires an hour prior to surgery for placement, resulting in a longer day for the patient, and disallowing surgeons to schedule early morning lumpectomies
• Having a wire protruding out from the breast can cause additional anxiety and pain for many patients
• There are times when the wire has been moved or the tip is difficult to locate and palpate during surgery, making it harder to remove the tumor and the marker clip with good margins

Radioactive seed localization (RSL) offers a new alternative. With this procedure, a radiologist uses mammography to place a very low-energy radioactive seed into the abnormal tissue or tumor. During the surgery, the surgeon uses a handheld device that detects radioactivity to more precisely identify the location of the tumor. 

Radioactive seeds are the size of a grain of rice and are completely sealed tiny capsules that contain a minute amount of radioactive iodine for detection, are often easier to place than wires, are more comfortable for the patient, and can be placed up to 10 days in advance of surgery. 

Studies indicate that RSLs have a reduced incidence of positive margins and allow for improved surgical approach in the removal of lesions. This is not only beneficial clinically, but the accuracy also means the removal of less unnecessary tissue, which may improve cosmetic results with lumpectomy, as well as minimize the need for take-back to surgery for additional margins.

RSLs emit a different energy than Tc-99m, the isotope used for sentinel node injections, and thus can be detected and differentiated in the OR with a radioactive probe, so a sentinel node biopsy can be performed concurrently. Sentinel axillary lymph node biopsy has abbreviated axillary surgery in breast cancer management and has lowered the incidence of lymphedema associated with more extensive axillary node removal.