Axillary Ultrasound and Fine-Needle Aspiration in the Preoperative Evaluation of the Breast Cancer Patient: An Algorithm Based on Tumor Size and Lymph Node Appearance

The objective of our study was to evaluate the utility of ultrasound-guided fine-needle aspiration (FNA) of the axillary lymph nodes in breast cancer patients depending on the size of the primary tumor and the appearance of the lymph nodes. Data were collected about tumor size, lymph node appearance, and the results of ultrasound-guided FNA and axillary surgery of 224 patients with breast cancer undergoing 226 ultrasound-guided FNA. Lymph nodes were classified as benign if the cortex was even and measured < 3 mm, indeterminate if the cortex was even but measured ≥ 3 mm or measured < 3 mm but was focally thickened, and suspicious if the cortex was focally thickened and measured ≥ 3 mm or the fatty hilum was absent. The results of ultrasound-guided FNAs were analyzed by the sonographic appearance of the axillary lymph nodes and by the size of the primary tumor. The sensitivity and specificity of ultrasound-guided FNA were calculated with axillary surgery as the reference standard. The sensitivity and specificity of axillary ultrasound to predict the ultrasound-guided FNA result were calculated. Of the 224 patients, 51 patients (23%) had a positive ultrasound-guided FNA result, which yields an overall sensitivity of 59% and specificity of 100%. The sensitivity of ultrasound-guided FNA was 29% in patients with primary tumors ≤ 1 cm, 50% in patients with tumors > 1 to ≤ 2 cm, 69% in patients with tumors > 2 to ≤ 5 cm, and 100% in patients with tumors > 5 cm. The sensitivity of ultrasound-guided FNA in patients with normal-appearing lymph nodes was 11%; indeterminate lymph nodes, 44%; and suspicious lymph nodes, 93%. Sonographic characterization of lymph nodes as suspicious or indeterminate was 94% sensitive and 72% specific in predicting positive findings at ultrasound-guided FNA. Ultrasound-guided FNA of the axillary lymph nodes is most useful in the preoperative assessment of patients with large tumors (> 2 cm) or lymph nodes that appear abnormal.