Retrieval of the Clipped Axillary Lymph Node and Its Impact on Treatment Decisions.

Simple Summary: Around 30% of breast cancer patients have axillary lymph node metastases present at the time of diagnosis. Historically, axillary lymph node dissection was performed in these patients with significant morbidity associated with the procedure including permanent lymphedema. These patients are now often treated with neoadjuvant chemotherapy to attempt to downstage the axilla and avoid axillary lymph node dissection. To reduce the false negative rate of a sentinel lymph node biopsy, a targeted axillary dissection is often performed to ensure that biopsy-proven metastatic axillary nodes are removed. The aim of our study was to determine how often the clipped node was also a sentinel lymph node, to identify factors that were associated with pathologic complete response following neoadjuvant chemotherapy, and to assess how the clipped node impacted final treatment decisions. These findings aim to help understand and guide surgeons on axillary evaluation after neoadjuvant chemotherapy. We examined clinically node-positive (cN+) breast cancer patients undergoing neoadjuvant chemotherapy and clipped lymph node (CLN) localization to determine the rate of CLN = non-sentinel lymph node (SLN), the factors associated with cN+ to pN0 conversion, and the treatment impact. We conducted a single institution review of cN+ patients receiving NAC from 2016 to 2022 with preoperative CLN localization (N = 81). Demographics, hormone receptor (HR) and HER2 status, time to surgery, staging, chemotherapy regimen, localization method, pathology, and adjuvant therapy were analyzed. Pathologic complete response (pCR) of the CLN was observed in 41 patients (50.6%): 18.8% HR+/HER2−, 75% HR+/HER2+, 75% HR−/HER2+, and 62.5% triple-negative breast cancer (p-value = 0.006). CLN = SLN in 68 (84%) patients, while CLN = non-SLN in 13 (16%). In 14 (17.3%) patients, the final treatment was altered based on +CLN status: 11 patients underwent axillary lymph node dissection (ALND), and 3 had systemic treatment changes. pCR rates varied, with the highest conversion rates observed in HER2+ disease and the lowest in HR+/HER2− disease. In 2 (2.5%) patients, adjuvant therapy changes were made based on a non-sentinel CLN, while in 97.5% of patients, a SLN biopsy alone represented the status of the axilla. This demonstrates that a +CLN often alters final plans and that, despite also being a SLN in most cases, a subset of patients will be undertreated by SLN biopsy alone. [ABSTRACT FROM AUTHOR]