Sentinel Lymph Node Positivity in Clinically Node Negative Breast Cancer Patients After Neoadjuvant Chemotherapy: Opportunities to Defer Intraoperative Frozen Section Analysis
Qutob O, Bensenhaver J, Susick L, Petersen L, Lehrberg A, Dimaano F, and Schwartz T. Sentinel Lymph Node Positivity in Clinically Node Negative Breast Cancer Patients After Neoadjuvant Chemotherapy: Opportunities to Defer Intraoperative Frozen Section Analysis. Ann Surg Oncol 2022; 29(SUPPL 2):421-421.
Ann Surg Oncol
INTRODUCTION: Neoadjuvant chemotherapy (NACT) is frequently implemented in a breast cancer treatment plan. In clinically node negative (cN0) patients following NACT, it is routine to perform sentinel lymph node (SLN) biopsy with intraoperative frozen section analysis with subsequent axillary lymph node dissection (ALND) if metastatic disease were detected. We aim to define the rate of sentinel node positivity (ypN1 (sn)) at our institution in patients who presented as cN0 and received NACT.
METHODS: Using our IRB approved breast cancer database a retrospective chart review was performed for all T1-T3, cN0 primary breast cancer cases who underwent NACT from 2016 to 2021 and have undergone a subsequent definitive operation at our institution. Demographics, clinical characteristics, tumor biology and staging were recorded. We stratified by hormone receptor (HR) and HER2 status defined as: HR negative (0%), HR weakly positive (1-10%), HR positive ( >11%), HER2 negative (0, 1+, 2+ negative by FISH), HER2 positive (3+, 2+ positive by FISH).
RESULTS: We identified 139 cN0 cases undergoing NACT from 2016 to 2021. Forty were excluded, leaving 99 for analysis. Of these, 8 (8 %) were found to be ypN1(sn). Of the 71 HER2 negative cases, we found 32 HR negative (triple negative) and 11 HR weakly positive, none of which (0%) were found to be ypN1(sn), and 28 HR positive of which 7 (25%) were found to be ypN1(sn). Of the 28 HER2 positive cases, we found 11 HR negative and 3 HR weakly positive cases, none of which (0%) were found to be ypN1, and 14 HR positive of which 1 (7%) was found to be a micrometastasis (ypN1mic(sn)).
CONCLUSIONS: Our results show that for the more aggressive tumor subtypes, including HR negative and HR weakly positive, the rate of ypN1(sn) after NACT in cN0 patients was 0%. These results suggest that frozen section could be avoided at the time of surgery for these patients in lieu of permanent pathology, due to he negligible likelihood of finding ypN1(sn) and thus needing ALND.