To evaluate the pathological response and influencing factors of axillary lymph nodes in patients with ER-negative/HER2-positive breast cancer after neoadjuvant therapy.

From November 2010 to December 2015, one hundred patients with HER2-positive, stage Ⅱa-Ⅲc breast cancer in Zhongshan City People’s Hospital were enrolled and evaluated for axillary status by palpation and fine needle aspiration (FNA) before neoadjuvant chemotherapy (NAC). All patients received 4-6 cycles of PCrb (paclitaxel 175 mg/m² and carboplatin AUC=6 every 3 weeks), and some patients combined with trastuzumab (6 mg/kg every 3 weeks).

Sixty-two patients were confirmed positive axillary lymph nodes by FNA (group A), and thirty-eight patients were considered negative axillary lymph nodes by FNA or palpation (group B). The axillary lymph node pathological negative node rate (pNNR) was 53.2% in group A and 71.1% in group B. The pNNR of ER-negative/HER2-positive was the highest (81.0% in group A and 86.7% in group B). In multivariate analysis, combined trastuzumab and ER status were independent factors predicting pNNR in HER2-positive breast cancer.

For breast cancer patients with positive lymph nodes before NAC, the ER-negative/ HER2-positive subtype is a potential type of patients with negative sentinel lymph nodes that do not require axillary lymph node dissection after NAC combined with targeted therapy.