Preoperative staging of the axilla in women with invasive breast cancer

SUMMARY Axillary node status is an important prognostic factor in invasive breast cancer. Axillary lymph node dissection (ALND) was previously the primary management approach; however, sentinel node biopsy (SNB) has largely replaced ALND, which is currently predominantly used to manage SNB-positive patients. Preoperative imaging-based staging of the axilla (with ultrasound, PET or MRI) for the detection of suspicious nodes has been applied to inform and potentially streamline axillary surgical management. Ultrasound with ultrasound-guided needle biopsy is the most accurate imaging-based strategy and has been shown to have clinical utility for preoperative axillary staging. A meta-analysis has reported a median sensitivity of 79.4% and a specificity of 100% for ultrasound-based staging, and estimated that ultrasound-guided needle biopsy triages 55.2% of women with metastatic axillary nodes (or a median of 17.7% of patients) directly to ALND, thereby avoiding unnecessary SNB. Although ultrasound-based staging has had a role in preoperative axillary assessment, it appears likely that this role will be shaped in the future by the ongoing evolution in surgical management of the axilla, particularly in light of recent evidence that challenges the need for ALND in some SNB-positive patients.