Sentinel lymph node metastasis after neoadjuvant treatment in breast cancer: Any size matters?

One of the advantages of neoadjuvant chemotherapy (NAC) treatments is its ability to convert patients who need a mastectomy in breast conservative surgery. NAC has also increased the conversion of node positive patients into node negative in around 40% allowing the use of sentinel node biopsy (SLN) in this setting. Timing of SLN biopsy after NAC has been a subject of debate. In patients with clinically node negative before NAC, rates of success and false negative rates of SLN after NAC are similar to those in the adjuvant setting, so SLN after NAC in previous negative axilla has been incorporated in the staging of the axilla. More controversial is its use in patients with positive axillary nodes before NAC who convert to node negative after NAC. Several randomized studies have reported the identification rates and the false negative rates of the SLN after NAC, concordant in the importance of surgical technique. As there is an agreement in the abandon of the immunohistochemistry (IHC) for SLN in the adjuvant setting as SLN IHC detected metastasis appear to have no impact on overall survival, in patients with SLN after NAC the inclusion of isolated tumor cell (ITC) as positive nodes lowers the false negative rates of the technique, suggesting the importance of assessing the SLN by IHC after NAC and considering it as residual disease. Longer follow up is needed to determine the prognostic implications of ITC in the SLN after NAC.