Assessing the Feasibility of Preoperative Axillary Ultrasound in Identifying Node-Negative Axillae: An Indian Retrospective Experience

Background and Objectives: Preoperative axillary ultrasound (PAUS) is a non-invasive method to assess nodal metastasis in breast cancer. Although sentinel lymph node biopsy (SLNB) is the gold standard, PAUS may help identify patients who can safely omit SLNB. This study evaluates PAUS’s diagnostic accuracy in predicting axillary nodal negativity (N0) in early-stage breast cancer. Methods: This retrospective study included 165 patients with confirmed early-stage breast cancer, excluding those with prior malignancies, neoadjuvant chemotherapy, or palpable axillary lymphadenopathy. PAUS classified nodes as positive or negative using stringent sonographic criteria, and findings were correlated with SLNB histopathology. Accuracy for detecting negative axillae, performance in patients meeting SOUND trial criteria, and overall diagnostic parameters were calculated. Results: Of the 165 patients, 86 were identified as node negative on PAUS, with a 90.69% accuracy for detecting negative nodes. For the full cohort, PAUS showed a sensitivity of 86.20%, specificity of 71.02%, positive predictive value of 61.72%, negative predictive value of 90.47%, and overall accuracy of 76.36% for identifying nodal status. Significant nodal features included shape, fatty hilum, and margins (p < 0.001), along with primary tumor size (p = 0.004). Histopathological findings such as extranodal extension (p < 0.001) and lymphovascular invasion (p < 0.001) were also significant. Conclusions: PAUS demonstrated high accuracy for identifying negative axillae and strong sensitivity and NPV, indicating it may identify node-negative patients who may forgo SLNB. These results support PAUS as a valuable tool for axillary surgery de-escalation, with further prospective validation recommended.