Does neoadjuvant chemotherapy reduce axillary lymph node dissection in postmenopausal ER+/HER2 <i>−</i> breast cancer?

Abstract

e12634 Background: The role of neoadjuvant chemotherapy (NAC) in postmenopausal estrogen receptor–positive/human epidermal growth factor receptor 2–negative (ER+/HER2−) breast cancer is debated. These tumors are typically less chemo-sensitive, with low rates of nodal pathologic complete response. Despite this, abnormal imaging findings may prompt escalation to NAC in patients with limited nodal disease. We evaluated whether NAC in this population meaningfully reduces the need for axillary lymph node dissection (ALND). Methods: We performed a retrospective analysis of postmenopausal ER+/HER2− breast cancer patients treated at a single institution between 2023 and 2025. Inclusion criteria included baseline cN1 disease defined by axillary ultrasound. The primary endpoint was the rate of ALND avoidance, defined as successful downstaging to SLNB alone, compared between patients treated with NAC versus upfront surgery. Statistical comparisons were performed using Fisher’s exact tests. All analyses were conducted using R version 4.5.3 (RStudio). Results: Of 292 eligible patients, 55 (19%) presented with ultrasound-defined cN1 disease. Among this cN1 cohort, 36 (65%) proceeded to upfront surgery without receiving NAC while 19 (35%) received NAC. Among patients who did not receive NAC, 25 (69%) underwent SLNB alone while 11 (31%) required ALND. Paradoxically, the NAC cohort had a higher rate of requiring ALND compared to the upfront surgery group (58% [11/19] vs. 31% [11/36]; p=0.08; Table 1). Successful surgical de-escalation (SLNB alone) was achieved in only 42% of the NAC group compared to 69% of the non-NAC group. Conclusions: In postmenopausal ER+/HER2− breast cancer with limited nodal disease, the use of NAC does not reliably translate into avoidance of ALND. These findings raise concern for imaging-driven escalation of neoadjuvant therapy without consistent surgical de-escalation and highlight the need for more selective use of NAC in this population. Surgical management of cN1 disease by NAC exposure. Cohort n SLNB Alone Required ALND P-value No NAC 36 25 (69%) 11 (31%) NAC 19 8 (42%) 11 (58%) 0.08