Disease	Breast cancer
Stage of Disease/Treatment	Neoadjuvant
Prior Therapy	None
Type of Study – 1	Phase II
Type of Study – 2	Single arm
Primary Endpoint	False negative rate of clipped nodes on axillary staging
Secondary Endpoint	Factors affecting nodal pathologic complete response
Additional Details of Endpoints or Study Design
Newly diagnosed patients with invasive breast cancer going for neoadjuvant chemotherapy with histologically proven metastatic axillary nodal burden and one to three abnormal lymph nodes on ultrasound were recruited. Patients with stage IV disease or more than three abnormal lymph nodes on ultrasound were excluded. All recruited patients underwent a dedicated axillary ultrasound in addition to their mammogram and breast ultrasound evaluation. An abnormal axillary lymph node was defined as having any of the following sonographic features: cortical thickness more than 3 mm or marked fatty hilar effacement. In these patients, the sonographically most suspicious lymph node was first biopsied. If proven metastatic, this particular lymph node would be clipped at a second setting and designated as the first clipped node. During the same second setting, the rest of the sonographically abnormal lymph nodes would undergo ultrasound guided fine needle cytology and clipping was performed for all malignant nodes. Patients with multiple nodes would have each node clipped with a different type of metallic marker to aid individual node identification. The clips used included UltraCor Twirl, HydroMARK, and UltraClip dual trigger markers. The choice of clip was determined by the performing radiologist's preference. After neoadjuvant chemotherapy, all patients underwent SMART and ALND. The clip in the clipped node specimen was confirmed by specimen x‐ray and pathological examination. All patients then underwent neoadjuvant chemotherapy.
Investigator's Analysis	Active and should be pursued further