Sentinel Node Biopsy After Neoadjuvant Chemotherapy in Initial Node-Positive Patients: Why or Why Not?

Sentinel lymph node (SLN) dissection provides a minimally invasive approach for axillary staging in breast cancer and is the standard of care in patients with clinically node-negative disease. In patients with node-positive dis-ease, the traditional approach has been axillary lymph node dissection (ALND). After neoadjuvant chemotherapy, ap-proximately 40 % of patients will be converted from clinically node positive to pathologically node negative raising significant interest in evaluating the role of SLN dissection in this clinical setting. Several clinical trials have evaluated the feasibility and accuracy of SLN dissection after neoadjuvant chemotherapy in patients with node-positive disease including ACOSOG Z1071, SEN-TINA, and SN FNAC. In these trials, the false negative rate of the procedure has been reported to be >10 % when SLNs are evaluated by hematoxylin and eosin staining. However, there are several factors which have been identified to be associated with improved accuracy including the number of SLNs examined and the use of dual tracer lymphatic mapping. The SN FNAC trial also reported improved accuracy when immunohistochemistry was used in SLN evaluation. Patient selection is an important con-sideration as those with a low likelihood for residual disease and high likelihood of pathologic complete response are the most likely to benefit from this approach. Although, ALND remains the standard of care in these patients, there may be a selective role for SLN dissection in this setting. An alternative approach targeting removal of the known axillary disease in addition to SLN dissection may improve accuracy and is the focus of current investigation.