Negative predictive value of ipsilateral axillary ultrasound in the pre-operative assessment of invasive breast cancer.

Abstract

e12080 Objective: To determine if a negative preoperative axillary ultrasound predicts a negative sentinel lymph node biopsy at surgery. Background: Axillary lymph node involvement is an important prognostic indicator in patients with breast cancer. Sentinel lymph node biopsy (SLNB) is currently the gold standard for determining the presence or absence of axillary metastases. Pre-operative axillary ultrasound is often used to evaluate axillary lymph node status prior to surgery and SLNB. Although there are no established guidelines on when preoperative axillary ultrasound is performed, at our institution we evaluate the axilla when invasive breast cancer is suspected. This study evaluated the negative predictive value (NPV) of axillary ultrasound compared to the pathology results of SLNB. Methods: In this single-center IRB-approved retrospective study, 3 years of breast imaging data (2014-2016) were reviewed. 137 patients had pathology verified invasive breast cancer with negative preoperative axillary ultrasound and subsequent SLNB. All patients had clinically negative axillae. Based upon the pathology results of SLNB, the negative predictive value of preoperative axillary ultrasound was calculated. Negative axillary ultrasound is defined as the absence of morphologically abnormal lymph nodes on imaging. A lymph node is considered morphologically normal when there is preserved fatty hilum and a uniform cortex measuring 3 mm or less. Results: Out of 137 patients with invasive breast cancer who had negative preoperative axillary ultrasound, 122 had negative SLNB results and 15 had positive SLNB results. Preoperative axillary ultrasound demonstrated a NPV of 89.1% for the detection of axillary metastatic disease at the time of SLNB. Conclusions: Negative axillary ultrasound excluded axillary metastatic disease in 89.1% of patients. This data suggests that negative axillary ultrasound may have a role in the setting of failed SLNB (no lymph nodes found at the time of surgery) in deciding whether to pursue axillary dissection.