Axillary sentinel node biopsy after neoadjuvant chemotherapy.

INTRODUCTION

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.

PATIENTS AND 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 <or=2 cm; p=0.004), positive extra-sentinel lymph node extension (versus negative; p=0.002) were more likely to have metastatic non-SLN(s).

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.