The Value of Ultrasound in Patients with T1–T2 Breast Cancer with No Palpable Lymph Nodes Enrolled in the EORTC 10981–22023 AMAROS Trial

Background: The use of axillary ultrasound (AUS) in breast cancer staging varies across international guidelines, ranging from routine use to targeted implementation. This study evaluates the clinical utility of AUS in patients enrolled in the AMAROS trial. Methods: Between 2001 and 2010, patients with early-stage breast cancer (cT1-T2N0M0) were enrolled in the European Organisation for Research and Treatment of Cancer (EORTC) phase III non-inferiority AMAROS trial by 34 European sites. cN0 status was determined either by clinical examination (w/oAUS) or AUS. All patients underwent sentinel lymph node biopsy (SLNB); those with tumor-positive SLNB (SLNB+) were randomized to axillary lymph node dissection (ALND) and axillary radiotherapy (ART). Results: In total, 4806 patients were included, of which 1425 SLNB+ patients were randomized. AUS was performed in 3020 (63%) patients. No differences in SLNB results between AUS groups were observed; a positive SLNB was found in 30% of AUS patients and in 32% of w/oAUS patients (p = 0.266). For the SLNB+ patients randomized in the AMAROS trial (n = 1425), baseline characteristics were comparable, except for a significantly higher number of AUS patients in the trial enrollment years between 2006 and 2010 (63%) compared with 2001–2005 (38%) (p < 0.001). Axillary tumor load did not differ between AUS groups (p = 0.156). Conclusions: In patients with cT1-2 breast cancer included in the AMAROS trial, sentinel lymph node involvement did not differ between patients who received pre-operative staging with AUS and those who were staged with clinical examination only.