A comparison of sentinel node biopsy before and after neoadjuvant chemotherapy: timing is important

Sentinel node identification rates are significantly better when mapping is performed before neoadjuvant chemotherapy (100% vs 80.6%), with failure to map correlated with clinically positive nodal disease at presentation and residual disease at axillary lymph node dissection. Among patients who map successfully after chemotherapy, the false-negative rate is high (11%). Given these findings, we currently recommend SNB before neoadjuvant chemotherapy for clinically node-negative patients, and raise concerns about the use of SNB after neoadjuvant therapy in patients with an initially clinically positive axilla.