Background/objective: Recent prospective trials support the use of sentinel lymph node biopsy (SLNB) in breast cancer patients after neoadjuvant chemotherapy (NAC) with a lower false-negative rate if three or more sentinel lymph nodes (SLNs) are identified. In this study, we investigated whether the pre-NAC axillary lymph node status influences the number of SLNs identified.
Methods: Stage I-III breast cancer patients who received NAC and underwent SLNB from May 2014 to April 2016 were identified from an institutional prospective database. Clinical and pathological factors among clinically node-negative (cN-) and clinically node-positive (cN+) patients who converted to cN- post-NAC were compared. Generalized linear mixed models analyzed factors associated with the number of SLNs removed.
Results: Among 343 patients who underwent SLNB during the study period, 335 (98%) had at least one SLN identified, and subsequently comprised the study population. The median number of SLNs identified was 4 (range 1-14), which did not differ according to pre-NAC nodal status (P = 0.15). Overall, 85% of patients had three or more SLNs identified (80% cN- group vs. 89% cN+ group; P = 0.02). On univariable analysis, age < 50 years and presenting with a positive axillary node were significantly associated with identifying three or more SLNs.
Conclusions: Our study confirms that SLNB was successfully performed in 98% of our patients after NAC, with very few failed mapping procedures. In the post-NAC setting, the median number of SLNs identified was four, and the status of the axilla prior to NAC did not negatively affect the number of SLNs identified.