RESUMEN
PURPOSE: To assess the safety and effectiveness of magnetic seeds in preoperative localization and surgical dissection of metastatic axillary lymph nodes (LN+) in breast cancer patients with axillary involvement, after neoadjuvant chemotherapy (NAC). In addition, to assess the impact of targeted axillary dissection (TAD) in reducing the rate of false negatives (FN) in sentinel lymph node biopsy (SLNB). MATERIALS AND METHODS: A cross-sectional prospective cohort study was conducted from April 2017 to September 2019, including breast cancer patients with axillary lymph node involvement treated with NAC. Prior to NAC, the LN+ were marked by ultrasound-guided clip insertion. After NAC, a magnetic seed (Magseed®) was inserted in the clip-marked lymph node (MLN). During surgery, the MLN was located and removed with the aid of a magnetic detection probe (Sentimag®) and the sentinel lymph node was removed. Axillary lymph node dissection (ALND) was used to determine the rate of FN for SLNB alone and the combination of SLNB and MLN dissection, called TAD. RESULTS: The study included 29 patients (mean age, 55; range, 30-78 years). Selective preoperative localization and surgical dissection were successful for all 30 MLNs (100%). The MLN corresponded to the SLN in 50% of cases. After ALND, there were 21.4% (3/14) FN with SLNB alone and 5.9% (1/17) with TAD. CONCLUSIONS: Following NAC, selective surgical removal of MLN by preoperative localization using magnetic seeds is a safe and effective procedure with a success rate of 100%. Adding TAD reduces the rate of FN associated with SLNB alone.