Outcomes of Sentinel Lymph Node Biopsy for Patients With Node-positive Breast Cancer Treated With Neoadjuvant Chemotherapy

Background/Aim: Clinical trials have shown that the sentinel lymph node biopsy (SLNB) is feasible for patients with cN1 breast carcinoma treated with neoadjuvant chemotherapy (NAC). This study aimed to evaluate the technical outcomes of SLNB by assessing the volume of residual nodal disease. Patients and Methods: All patients with cT1-3 cN1 breast cancer undergoing NAC from January 2018 to December 2021 were retrospectively identified from our institutional database. We assessed the outcomes of preoperative clinical examination, ultrasonography, and other imaging to predict the axillary nodal status after NAC for patients converted to cN0 and undergoing SLNB; both adequate mapping and false-negative rate (FNR) at intraoperative evaluation of SLN were assessed. Results: Overall 160 patients were included in the study; 98 were converted to cN0 and underwent SLNB. No difference was found in the adequate mapping rate nor in the mean number of SLNs retrieved compared to the residual LN burden. The intraoperative SLN FNR was 38.2%, with smaller nodal volume being associated with lower FNR (p<0.01). The positive predictive values of physical examination and imaging-based nodal assessment post-NAC were 87.1% and 68.2%, respectively. Conclusion: In a significant percentage of patients with cN1 disease converted to cN0 after NAC, it was possible to recover three or more SLNs. The residual volume of LN disease did not impact the SLN mapping rate. However, we found a high FNR for intraoperative SLN evaluation, particularly for patients with small residual nodal disease. It seems that only a small proportion of patients eligible for SLNB after NAC can be spared ALND.