ABS ePoster Library

Introduction
Accurate preoperative axillary staging in breast cancer patients is important to allow decisions regarding neoadjuvant treatment, and to avoid sentinel node biopsy. A few studies have suggested reduced sensitivity of ultrasound in preoperative axillary staging in lobular cancer compared to ductal. We evaluated the accuracy of preoperative axillary staging for lobular cancer in comparison to ductal cancer in the West of Scotland.
Methods
Patients with invasive lobular or ductal breast cancer, diagnosed in all breast units of the West of Scotland between 2012 and 2014, who underwent axillary surgery, were identified from the prospectively maintained Managed Clinical Network database. Data including clinicopathological characteristics, preoperative axillary ultrasound, core biopsy and FNA results, and final operative pathology were collated from the same database. Sensitivity of preoperative axillary ultrasound in the lobular and ductal cohorts was calculated. Statistical significance was calculated using Chi square test.
Results
602 patients with invasive lobular and 4199 patients with invasive ductal cancer, who underwent axillary surgery, were identified. 211(35%) lobular patients ultimately had positive axillary pathology, of which 67 had an abnormal (U3-5) preoperative axillary ultrasound. Ultrasound sensitivity for nodal disease was 32.1% in the lobular cohort (Negative Predictive Value:71.6%) compared to 50.1% in the ductal cohort (NPV:77.3%) (p<0.001). For high-burden axillary disease (3+ positive nodes) sensitivity was 49.4% and 68.1% respectively (p=0.001).
Conclusions
Sensitivity of axillary ultrasound is significantly reduced in lobular breast cancer. We suggest considering biopsy of ultrasonographically normal nodes when the clinical suspicion for axillary involvement is relatively high in lobular cancer.