To Accurately Assess Lymph Node Response to Neoadjuvant Chemotherapy by Wire Localization of Clip-marked Axillary Lymph Nodes in Breast Cancer Patients

The investigator developed this protocol to accurately assess lymph node response to neoadjuvant chemotherapy in cN1 breast cancer patients. In brief, pathologically proven positive axillary lymph node will be clip-marked before the initiation of neoadjuvant chemotherapy (NACT) and continuously monitored through out the course of chemotherapy with ultrasound. After the completion of neoadjuvant chemotherapy, a wire will be placed to localize the clip-marked node before surgery. During surgery, a standard sentinel lymph node biopsy will be performed as well as the removal of the wire localized node. Axillary lymph node dissection (ALND) will be performed in all participants. Accuracy of SLNB alone and in combination with the removal of wire-localized-clip-marked nodes will be analyzed. Axillary ultrasound and CT scan will be performed before and after neoadjuvant chemotherapy for all patients enrolled. By assessing clinical-pathological and imaging data acquired from this trial, the investigator look forward to developing a model to accurately predict lymph node pCR (AUC >0.85) so as to safely avoid axillary lymph node dissection in cN1 breast cancer patients.