To determine the feasibility of sentinel lymph node biopsy (SLNB) in this study, the investigators evaluated the false-negative rate (FNR) of SLNB. The FNR was calculated as the number of patients with negative SLNs who had a residual disease in the rest of the axillary lymph nodes (ALNs) divided by the total number of patients with residual disease in either the SLNs, the rest of the ALNs, or both: FN/true-positive + FN. The investigators compared the FNR of the SLNB according to the radiologic response measured using breast MRI in each subtype. The investigators further evaluated the FNR in subgroups stratified by clinical nodal stage. Additionally, the investigators assessed additional metastatic ALNs in cases with 1-2 metastatic SLNs through the completion of ALN dissection.
