Predicting the extent of nodal disease in early breast cancer.

95 Background: In early-stage breast cancer patients, the number of positive lymph nodes (LN) is considered in decisions regarding surgery and radiation. The goal of this study was to characterize the extent of axillary nodal involvement based on clinicopathologic and imaging features. Methods: A prospective database was used to identify T1-2 patients who underwent regional nodal ultrasound (US) and axillary lymph node dissection (ALND) from 2002-2012. Patients who received neoadjuvant chemotherapy or had extra-axillary LN metastases were excluded. Subjects were grouped by whether axillary metastases (AxM) were identified by US confirmed by needle biopsy or by sentinel lymph node dissection (SLND) after a negative US, then compared using X2 and Rank-Sum tests as appropriate. Results: AxM were identified by US in 190 patients and SLND in 518 patients. When compared to US-detected patients, SLND patients had fewer positive nodes (2.2 vs. 4.1, p < 0.0001), smaller metastases (5.3 vs. 13.8 mm, p < 0.0001), an...