Triple Technique (Radioisotope, Blue Dye, and Embedded Fiducial Marker) for Identifying Sentinel Lymph Nodes Following Neoadjuvant Chemotherapy for Clinical Lymph Node Positive Breast Cancer; Is More Really Better?

[PURPOSE] To determine the accuracy of radioisotope, blue dye and implanted fiducial marker for identification of the histopathologically positive percutaneous/previously biopsied lymph node (PBLN) following neoadjuvant chemotherapy (NAC). Detection of the PBLN is critical for monitoring disease response and guiding subsequent treatment decisions. However, conventional sentinel lymph node biopsy (SLNB) techniques have shown unacceptable false negative rates. Recommendations for improvement suggest using dual tracers, removing more lymph nodes and implantable markers in the PBLN. This study evaluated the accuracy of PBLN identification using each of the 3 most common localization techniques: blue dye (lymphazurin), radioisotope (Technetium-99m sulfur colloid), and implanted fiducial marker (SAVI SCOUT).

[METHODS] Patients with PBLN marked with a SAVI SCOUT, with or without a metallic clip, and who received NAC were identified from our breast cancer surgery database. The accuracy of the 3 localizing techniques was evaluated. Secondary outcomes included total number of lymph nodes retrieved and number of sampling events per patient for each technique.

[RESULTS] We identified 65 patients who underwent percutaneous lymph node biopsy prior to NAC. The clip marking the PBLN was identified in 64 patients (98%). The PBLN was identified by the SAVI SCOUT in 61 (95%) of 64 patients, radioisotope in 44 (71%) of 62 patients and blue dye in 28 (64%) of 44 patients. A SAVI SCOUT was placed at the time of biopsy instead of a clip in 13 patients and identification of the PBLN was 100% for those patients. The mean number of lymph nodes removed with the SAVI SCOUT was 2.7, with radioisotope was 4.3 and with blue dye was 3.6 (P = .004). The mean number of SLN sampling events with the SAVI SCOUT was 1, with radioisotope was 2.0 (range: 0-6) and with blue dye was 1.8 (range: 0-5) (P < .005). When radioisotope was used, the clip was found in the hottest lymph node 40% of the time, in the second and third hottest lymph node 5% and 11% of the time, respectively. The clipped node was not hot in 29% of cases.

[CONCLUSIONS] This study demonstrates that the most accurate method for identifying the PBLN is with placement of a fiducial marker. Furthermore, the addition of radioisotope and blue dye may result in an excessive number of lymph nodes removed and more retrieval events during SLNB following NAC. Placement of the SAVI SCOUT marker at the time of percutaneous lymph node biopsy may subsequently obviate the need for additional mapping techniques of blue dye and radioisotope during sentinel lymph node surgery.