Fig. 1

History of axillary surgery and emerging techniques for the detection of axillary lymph node metastasis. Axillary lymph node dissection (ALND) was performed as a standard method for determining axillary lymph node (ALN) status breast cancer patients until the 1990s, which may cause inevitable complications, such as upper arm lymphedema, shoulder movement restriction, numbness or paresthesia and pain syndrome in the surgical area, seriously affecting the life quality of breast cancer patients. Over the decades, increasing evidence has shown that sentinel lymph node biopsy (SLNB) could be an alternative option for ALND in selected patients, with no significant influence on axillary recurrence or long-term survival. To improve the diagnostic performance of metastatic axillary lymph nodes and reduce postoperative complications, various emerging techniques have been used as noninvasive approaches preoperatively. Imaging methods including ultrasound, computed tomography, magnetic resonance imaging, have long been the main options for diagnosis. Recently, machine learning approaches, which can automatically classify metastatic ALNs, have shown promise in the diagnosis of ALN metastasis. Clinical prediction models that combine imaging features or biomarkers and clinical factors also provide additional information for clinical decision-making. ALND, axillary lymph node dissection; CT, computed tomography; MRI, magnetic resonance imaging. Created with BioRender.com