Dual role of intraoperative ultrasound in axillary surgery: enhanced detection and surgical de-escalation in breast cancer

BACKGROUND: Intraoperative ultrasound (IO-USG) may optimize axillary management in breast cancer surgery. This study evaluated IO-USG’s dual role in preventing unnecessary axillary lymph node dissection (ALND) and identifying additional nodal metastases missed by sentinel lymph node biopsy (SLNB). METHODS: This retrospective cohort study included 314 consecutive patients with invasive breast cancer who underwent SLNB with IO-USG evaluation between January 2019 and December 2023. IO-USG was performed after SLNB to identify suspicious non-sentinel nodes. Patients were categorized into SLNB-only, targeted axillary dissection (TAD), or ALND based on combined SLNB and IO-USG findings. RESULTS: Of 314 patients, 113 (36%) received neoadjuvant chemotherapy and 201 (64%) underwent upfront surgery. Final surgical management comprised SLNB-only in 244 (77.7%), TAD in 46 (14.7%), and ALND in 24 (7.6%) patients. Among 89 SLNB-positive patients, 68 (76.4%) avoided ALND through IO-USG guidance. IO-USG identified additional axillary metastases in 4 of 225 SLNB-negative patients (1.8%). Molecular subtype analysis revealed no IO-USG positivity in triple-negative cases (0/25), while HR+/HER2- tumors comprised 82.6% of IO-USG-positive cases. At a median follow-up of 33.2 months, no axillary recurrences occurred. CONCLUSION: IO-USG may support personalized axillary management, helping avoid ALND in 76.4% of node-positive patients while identifying additional axillary metastases in 1.8% of SLNB-negative cases. As a complementary technique to standard SLNB, it appears to provide selective utility based on tumor biology. TRIAL REGISTRATION: Not applicable.