Diagnostic Accuracy of Axillary Ultrasound for Detecting Metastatic Lymph Nodes in Breast Cancer Patients

Abstract

Background: Accurate assessment of axillary lymph node (ALN) involvement is critical for optimal management in breast cancer. Sentinel lymph node biopsy (SLNB) has reduced morbidity compared to complete axillary lymph node dissection (ALND), yet it remains an invasive procedure. Preoperative ultrasound (US) could help identify node-negative patients who may potentially avoid extensive surgery. Objectives: In this study, we aimed to evaluate the diagnostic performance of US in predicting metastatic ALNs compared to surgical pathology in a cohort of Iranian breast cancer patients. Methods: In this retrospective cross-sectional study, we evaluated 187 women with breast cancer (mean age 49.94 ± 11.32 years) treated from 2016 to 2021 at Shohada-e Tajrish Hospital, Tehran, Iran. All underwent preoperative US of the axilla followed by SLNB and/or ALND. We calculated US sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). "Strict" criteria defined only definitively malignant nodes as positive, whereas "expanded" criteria considered suspicious nodes as positive. Results: Of 187 patients, 158 (84.49%) underwent SLNB, with a mean of 3.61 ± 2.4 nodes examined (53/158 [33.54%] had metastases), and 55 (29.41%) underwent ALND, with a mean of 8.73 ± 5.00 nodes examined (21/55 [38.18%] positive). Using strict criteria, US sensitivity was 44.68%, specificity 81.11%, PPV 55.25%, NPV 73.74%. Expanded criteria improved sensitivity to 61.19% but reduced specificity to 60.83%. Neoadjuvant chemotherapy (NAC) [administered to 54 (28.9%)] further affected US accuracy. Conclusions: Expanded US criteria yielded higher sensitivity but lower specificity, underscoring the trade-off between detecting more true positives and overcalling benign nodes. Prospective multi-center trials are warranted to clarify whether an expanded approach can safely reduce invasive staging.