Axillary sentinel node biopsy after neoadjuvant chemotherapy.

Background: The role of sentinel lymph node biopsy (SLNB) in patients with locally advanced breast cancer (LABC) with potentially sterilized axillary lymph nodes after neoadjuvant chemotherapy (NAC) remains unclear.

Methods: Between 2002 and 2008, SLNB with both blue-dye and radioisotope injection was performed in 77 patients with LABC whose cytopathologically confirmed positive axillary node(s) became clinically negative after NAC. Factors associated with SLN identification and false-negative rates, presence of non-sentinel lymph node (non-SLN) metastasis were analyzed retrospectively.

Results: SLNB was successful in 92% of the patients. Axillary status was predicted with 90% accuracy and a false-negative rate of 13.7%. Patients with residual tumor size >2 cm had a decreased SLN identification rate (p=0.002). Axillary nodal status before NAC (N2 versus N1) was associated with higher false-negative rates (p=0.04). Positive non-SLN(s) were more frequent in patients with multifocal/multicentric tumors (versus unifocal; p=0.003) and positive lymphovascular invasion (versus negative; p=0.0001). SLN(s) positive patients with pathologic tumor size >2 cm (versus

Conclusions: SLNB has a high identification rate and modest false-negative rate in LABC patients who became clinically axillary node negative after NAC. Residual tumor size and nodal status before NAC affect SLNB accuracy. Additional involvement of non-SLN(s) increases with the presence of multifocal/multicentric tumors, lymphovascular invasion, residual tumor size >2 cm, and extra-sentinel node extension.