BACKGROUND

Axillary lymph node stage is important in guiding adjuvant treatment for breast cancer. The role of axillary ultrasound (AUS) in axillary staging is uncertain.

METHODS

From an institutional database, all newly diagnosed invasive breast carcinomas from February 1, 2011 to October 31, 2014 were identified; exclusions were for stage IV disease, palpable adenopathy, or receipt of neoadjuvant chemotherapy. AUS findings, categorized as suspicious versus not suspicious, were correlated with the number of nodal metastasis from surgical pathology. The false-negative rate of nonsuspicious AUS for identifying ≥3 lymph nodes positive on final pathology was calculated.

RESULTS

A total of 513 cancers were included. Overall, 400 AUSs were not suspicious (78%), and 113 were suspicious (22%). The sensitivity and specificity of AUS for predicting ≥3 nodal metastasis were 71 and 83%, respectively. The false-negative rate for detecting ≥3 nodal metastasis was 4%. False-negative rate was higher for lobular versus nonlobular carcinomas (12.0 vs. 2.3%, p = 0.004) and for pT2-pT4 tumors versus pT1 tumors (8.2 vs. 1.7 %, p = 0.005).

CONCLUSIONS

Patients with normal axillary physical exam and ultrasound rarely harbor a large nodal disease burden. Randomized trials of sentinel lymph node biopsy versus no axillary surgery in patients with normal AUS must be powered for subgroup analysis of patients with invasive lobular carcinoma and pT2-pT4 tumors. Preoperative identification of nodal metastasis may decrease the need for second surgeries and identify candidates for neoadjuvant chemotherapy. AUS is a noninvasive means of predicting disease burden preoperatively and as such is a powerful tool to individualize treatment plans.