Abstract PO5-23-02: Targeted Axillary Dissection with Paramagnetic Marker Localization

Abstract Background: Targeted axillary dissection (TAD), the combination of sentinel lymph node biopsy (SLNB) and targeted lymph node biopsy (TLNB), can reduce the false negative rates of SLNB alone dramatically in breast cancer patients, who received neoadjuvant chemotherapy (NACT). However optimal methods for TAD are still under investigation. A paramagnetic marker Magseed® was used for the identification of the TLN in this study. Methods: 80 patients eligible to receive NACT were included. All patients had positive axillary lymph nodes verified by core biopsy. Six patients did not receive NACT for any reason. After NACT the targeted lymph nodes (TLNs) were marked with Magseed®, a non-radioactive paramagnetic marker. The SLNs were marked with dual tracer method. The SLNB and the selective TLNB were performed in 74 patients. The Magseed® marked TLNs were identified with the Sentimag® probe and excised. Specimen x-ray was performed to confirm the Magseed® within the prior to NACT biopsied and clipped lymph node. The identification rates of TLNs and SLNs, and the concordance rates were calculated. Results: The TLN identification rate was 100% (74/74), the SLN identification rate was 81.1% (60/74), the concordance rate of TLN and SLN was 58.1% (43/74). In 66.2% (49/74) of the patients the TLN converted to negative, and no ALND was performed. When the TLN converted to negative, a SLN could not be identified in 18.4% (9/49) of the patients. In 33.8% (25/74) of the patients the TLN remained positive after NACT and ALND was performed. When the TLN remained positive, a SLN could not be identified in 40% (10/25) of the patients. Complications according Magseed® deployment or identification could not be observed. Conclusion: Magseed® is a reliable and feasible marker for the identification of TLNs after NACT. Citation Format: Roland Reitsamer, Andreas Sir, Ernst Forsthuber, Florentia Peintinger. Targeted Axillary Dissection with Paramagnetic Marker Localization abstract. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-23-02.