Accuracy of Ultrasound-Guided Core Biopsy for Staging Axilla in Clinically Node-Negative Patients with Invasive Breast Cancer Taking Histopathology as Gold Standard

Objective: To assess the accuracy of ultrasound-guided core biopsy in staging axillary lymph nodes in clinically node-negative invasive breast cancer patients using histopathology as the gold standard. Methods: This cross-sectional study was conducted in the Department of Pathology at Mekran Medical College, Turbat, Pakistan, from April 2023 to September 2023. The study included breast cancer patients who were clinically negative for lymph node involvement. Ultrasound-guided core biopsies were performed on suspicious axillary lymph nodes by experienced radiologists, with histopathological analysis serving as the gold standard. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy were calculated to assess diagnostic performance. Patient demographics, tumor characteristics, and axillary ultrasound findings were also recorded. Results: A total of 132 invasive breast cancer patients were included, with a mean age of 57.67 ± 13.03 years. The majority of patients were diagnosed with invasive ductal carcinoma, accounting for 113 (85.6%) cases. Hormone receptor positivity was prevalent, with estrogen receptor positivity in 119 (90.2%) and progesterone receptor positivity in 116 (87.9%) cases. The most common immunohistochemistry subtype was Luminal B, present in 66 (50%) patients, followed by Luminal A in 51 (38.6%) patients. Most tumors were of moderate grade 77 (58.4%) and early-stage (pT1) 63 (47.7%). Ultrasound-guided core biopsy exhibited a sensitivity of 87.9% and specificity of 100%, with positive and negative predictive values of 100% and 89.2% respectively, resulting in a diagnostic accuracy of 93.9%. Conclusion: Ultrasound-guided core biopsy demonstrates strong diagnostic performance in identifying metastatic axillary lymph nodes in clinically node-negative invasive breast cancer patients.