RESUMEN
INTRODUCTION: A controversial aspect of breast cancer management is the use of sentinel lymph node biopsy (SLNB) in patients requiring neoadjuvant chemotherapy (NCT). This paper discusses the detection rate (DT) and false negatives (FN) of SLNB after NCT to investigate the influence of initial nodal disease and the protocols applied. METHODS: Prospective observational multicenter study in women with breast cancer, treated with NCT and SLNB post-NCT with subsequent lymphadenectomy. DT and FN rates were calculated, both overall and depending on the initial nodal status or the use of diagnostic protocols pre-SLNB. RESULTS: No differences in DT between initial node-negative cases and positive cases were found (89.8 vs. 84.4%, P=.437). Significant differences were found (94.1 vs. 56.5%, P=0,002) in the negative predictive value, which was lower when there was initial lymph node positivity, and a higher rate of FN, not significant (18.2 vs. 43.5%, P=.252) in the same cases. The axillary study before SLNB and after the NCT, significantly decreased the rate of FN in patients with initial involvement (55.6 vs 12.5, P=0,009). CONCLUSIONS: NCT means less DT and a higher rate of FN in subsequent SLNB, especially if there is initial nodal involvement. The use of protocols in axillary evaluation after administering the NCT and before BSGC, decreases the FN rate in these patients.