Abstract: Objective To analyze the ultrasound features of patients with clinical axillary lymph node-positive breast cancer, and to explore the correlation of ultrasound features with lymph node metastasis burden and prognosis. Methods The patients with clinical node-positive disease who underwent axillary lymph node dissection in our center between January 2009 and December 2020 were included. The clinicopathological and ultrasonographic indicators that could predict the lymph node metastasis burden were retrospectively analyzed. Multivariable Cox regression was used to explore the ultrasonographic predictors affecting the prognosis. Results A total of 1,055 breast cancer patients were included in the study, including 398 patients (37.7%) with low nodal burden (1-2 lymph node metastases) and 657 patients (62.3%) with high nodal burden (≥3 lymph node metastases). Multivariable analysis indicated that the age of patients ≥55 years old (OR=1.56, 95%CI: 1.20-2.02, P=0.001), the ultrasound tumor size <20.0 mm (OR=1.54, 95%CI: 1.14-2.09, P=0.005), long diameter of lymph node <20.0 mm (OR=2.03, 95%CI: 1.48-2.79, P<0.001), short diameter of lymph node <8.6 mm (OR=1.41, 95%CI: 1.06-1.89, P=0.019) and 1-2 suspicious lymph nodes (OR=2.74, 95%CI: 1.63-4.61, P<0.001) were independently associated with low nodal burden. The progesteron receptor status and the long diameter of lymph node were independent predictors of disease-free survival (HR=2.06, 95%CI: 1.21-3.50, P=0.008; HR=1.66，95%CI: 1.15-2.40, P=0.007) and overall survival (HR=4.53, 95%CI: 2.18~9.59, P<0.001; HR=3.49，95%CI:1.96-6.20, P<0.001). Conclusions Ultrasound features can help predict lymph nodal metastasis burden and prognosis of patients with clinical axillary node?positive breast cancer, and guide subsequent individualized treatment.

Key words: Breast cancer, Clinical lymph node-positive, Lymph node metastasis burden, Ultrasound features, Sentinel lymph node biopsy, Prognosis