Magseed Magnetic Marker in Locating Axillary Lymph Nodes in Patients With Breast Cancer Undergoing Surgery

Inclusion Criteria: * Histologically confirmed cT0-4, N1 breast cancer * Axillary lymph node metastasis with pathologic confirmation by needle biopsy * Clip placed in the sampled axillary lymph node before completing chemotherapy * Received neoadjuvant chemotherapy prior to surgical resection * Scheduled for targeted axillary dissection (defined as selective localization and removal of the clipped node and sentinel lymph node dissection \[SLND\]) * Eastern Cooperative Oncology Group (ECOG) performance status 0-2 Exclusion Criteria: * Distant metastases * Inflammatory breast cancer * Prior surgical axillary procedure including SLND or axillary node excision * Prior history of breast cancer in the ipsilateral breast * History of lymphoma * The subject is known to be pregnant. Premenopausal patients under the age of 50 must have a pregnancy test performed as standard of care before the MagSeed is placed * Previous radiation to the breast or axilla * Pacemaker of other implantable device in the chest wall