Upadhyaya VS, et al. - Researchers sought to determine the preoperative breast cancer (BC) characteristics that influence the diagnostic efficiency of axillary ultrasound (US) and assess the reliability of US in the different subgroups of BC patients. They retrospectively reviewed axillary US assessments in 605 newly diagnosed invasive BC cases. Of these, 251 (41.5%) had nodal metastases. Axillary US had sensitivity of 75.7%, specificity of 92.9%, positive predictive value of 88.4%, negative predictive value of 84.4%, and false-negative rate of 24.3%. With invasive lobular cancer (ILC), grade I/II, unifocal, and smaller tumors, US sensitivity was low. In grade III, estrogen receptor (ER)-negative, progesterone receptor (PR)-negative, HER2-positive, triple-negative, and larger breast tumors, lower US specificity was observed. These findings suggest moderate sensitivity and good specificity of US in detecting metastatic axillary lymph nodes. Based on preoperative cancer characteristics, nodal metastases from ILC, unifocal, lower grade, and smaller breast tumors were related with less sensitivity to US. Further, US was less specific in grade III, ER-negative, PR-negative, HER2-positive, triple-negative, and larger breast tumors. They suggest practicing caution while interpreting the US axillary findings of patients with these preoperative tumor features.