I. Nwaogu1, Y. Yan1, J. A. Margenthaler1 1Washington University,Surgery,St. Louis, MO, USA
Introduction: Axillary ultrasound (AUS) has been used in an attempt to identify sub-clinical node-positive disease and improve clinical staging and treatment recommendations. We sought to identify clinicopathologic factors potentially related to false negative AUS results.
Methods: Patients with a clinically node-negative Stage I-II invasive breast cancer who also had a normal AUS were identified from our prospectively maintained database. All AUS studies were performed by dedicated breast radiologists and interpreted as “normal” according to the absence of specific characteristics previously shown to be more commonly associated with metastatic involvement. True- and false-negative AUS studies were compared statistically based on clinical, radiographic, and histologic parameters.
Results:Of the 118 patients with a normal AUS, 25 (21%) were ultimately found to be node-positive on final pathologic assessment following axillary surgery. On bivariate analysis, primary tumor size, lymphovascular invasion (LVI), and Her2neu receptor status were found to be significantly different between true- and false-negative AUS. The average tumor size was smaller in the true-negative group compared to the false-negative group [16 vs 21mm (p< 0.01)]. The presence of LVI was more likely in the false-negative group [11/25 (44%)] compared to the true-negative group [7/93 (8%)] (p< 0.0001). Her2neu receptor status was more likely amplified in the false-negative group [8/25 (32%)] compared to the true-negative group [13/93 (14%)] (p=0.037). No significant difference was noted between groups with regard to patient age, race, body mass index, tumor grade, histologic type, estrogen or progesterone receptor status, and time between AUS and axillary surgery. On multivariate analysis, only the presence of LVI achieved statistical significance (p=0.0007).
Conclusion:AUS is a valuable tool that accurately predicted absence of axillary disease in 79% of patients with clinically node-negative breast cancer. AUS findings may be less accurate in the setting of LVI, and a negative AUS in patients with this feature should be interpreted with caution.