New horizons in imaging and surgical assessment of breast cancer lymph node metastasis.

Axillary nodal status is one of the most important prognostic factors in breast cancer. While sentinel lymph node biopsy (SLNB) is a safe and validated procedure for clinically node-negative patients, axillary management of clinically node-positive patients has been more controversial. Patients with clinically detected axillary metastases often benefit from neoadjuvant chemotherapy (NAC). Those who convert to node-negative disease following NAC are important to identify, since they can often be spared significant morbidity from axillary dissection. SLNB has shown widely varying false-negative rates (FNR) but with the use of dual mapping and surgical biopsy of 3 or more nodes, it is considered an acceptable method to stage the axilla in clinically node-positive patients who receive NAC. Various methods including targeted axillary dissection (TAD) have been shown to decrease the FNR of SLNB. We will review appropriate methods to identify a metastatic node and subsequent ultrasound-guided biopsy with tissue marking techniques. We underscore key points in monitoring axillary response, techniques to accurately localize the biopsied and clipped known metastatic node for surgical excision and the effect of various methods in reducing the FNR of SLNB, including the emerging concept of TAD on patient care.