P170. Impact of neoadjuvant chemotherapy on axillary lymph node yield in breast cancer

Abstract

Introduction: Axillary lymph node (LN) status is an important prognostic indicator in breast cancer. Neoadjuvant chemotherapy (NAC) not only causes down staging of the primary tumour but also alters axillary disease status and morphology. Our research group has previously published on histo-morphological changes in axillary LNs, including scarring following NAC. The aim of this study was to assess the impact of NAC on axillary LN yield. Methods: A retrospective case control study was performed comparing breast cancer patients undergoing axillary lymph node dissection (ALND) following NAC to those without NAC, between 2009 and 2013. The primary outcome was median LN number reported; secondary outcomes included proportion of patients incompletely staged (<10 LNs) and proportion of positive LNs. Linear regression analysis was used to control for age, operating surgeon, and tumour prognostic features. Results: There were a total of 50 and 61 ALNDs in the NAC and control group respectively. The median LN yield was significantly lower in the NAC group, 15 vs. 19, p 1⁄4 0.002. There was a significantly greater proportion of incompletely staged patients in the NAC group 7 (14.0%) vs. 2 (3.3%), p 1⁄4 0.046. The proportion of positive LNs was not significantly different 21% vs. 15%, p 1⁄4 0.143. Linear regression revealed NAC was an independent predictor of reduced LN yield (B 1⁄4 4.214, p 1⁄4 0.008). Conclusions: NAC alters the morphology of the axilla and reduces the LN yield in ALND for breast cancer. Fewer nodes may be obtained in complete staging of the axilla following NAC.