Sentinel lymph node biopsy with blue dye after neoadjuvant chemotherapy in initially node negative and positive breast cancer

This study aimed to evaluate the efficacy of sentinel lymph node biopsy (SLNB) using blue dye-only in patients who underwent neoadjuvant chemotherapy (NACT) and the axillary recurrence rate in these patients. Additionally, we sought to investigate the impact of this approach on disease-free survival (DFS) and overall survival (OS). Patients who underwent SLNB with blue dye only after receiving NACT for breast cancer between 2013 and 2021 were retrospectively evaluated. The study included patients with invasive breast cancer who were clinically node-negative (cN0) or node-positive (cN1) at admission, received systemic NACT, and converted to clinically node-negative (ycN0) status at restaging. A total of 185 patients were included in this study; 68 patients with cN0 tumors remained ycN0 after NACT, and 117 patients with cN1 tumors regressed to ycN0 after NACT. The median age of patients was 44 (IQR 38–54) years. Our SLN identification rate was 91% in patients who were cN0 and 88% in those who were cN1 at admission. Overall, SLN was not identified in 20 patients (10.8%). The median follow-up was 59 (IQR, 45–81) months. There were 8 (4.3%) locoregional recurrences (6 breast/chest wall recurrences and 2 axillary recurrences) and 19 (10.3%) distant recurrences. There was no statistically significant difference between the cN0 and cN1 groups regarding locoregional or distant recurrences. No significant differences were observed between the cN0 and cN1 groups in terms of recurrence, DFS (p = 0.673), or OS (p = 0.610). Sentinel lymph node biopsy using blue dye only after neoadjuvant chemotherapy demonstrated acceptable identification rates and low axillary recurrence in this cohort. However, this approach should not be regarded as standard practice in patients with initially node-positive breast cancer. These findings may reflect feasibility in selected settings with limited resources or where dual-tracer mapping or targeted axillary dissection is not available. Further prospective studies with standardized axillary marking and longer follow-up are needed to confirm these outcomes.