BackgroundAxillary lymph node involvement is one important prognostic factor in breast cancer, but the way to access this information has modified over the years.This study evaluated if axillary ultrasound (US) coupled with fine needle aspiration cytology (FNAC) can better predict clinically relevant node metastasis than physical exam, in patients with breast cancer.MethodsThis is a cross-sectional study with retrospective data collection of 241 women with operable breast cancer who were submitted to preoperative axillary assessment by physical exam, US and FNAC if suspicious nodes by imaging. We calculated sensitivity, specificity, and accuracy of the methods. We compared the patient's characteristics using chi-square test, parametrics and non parametrics statistics according to the variable.ResultsThe most sensible method was US (0.59; 95% CI, 0.50-0.69) and the most specific was US coupled with FNAC (0.97; 95% CI, 0.92-0.99 ). Only 2,7% of the patients with normal axillary US had more than 2 metastatic nodes in the axillary lymph node dissection, against 50% of the patients with suspicious lymph nodes in the US and positive FNAC. ConclusionsWe found that axillary US and FNAC are more accurate than physical examination in detecting node metastasis in breast cancer patients. Moreover, axillary US coupled with FNAC can sort patients that have a few metastatic nodes at most from those with heavy axillary burden and could be one more tool to initially evaluate patients and define treatment´s strategies.