Identification of Risk Factors Associated with Axillary Lymph Node Metastasis for Sentinel Lymph Node-Positive Breast Cancer Patients.

Objective This study aimed to identify clinicopathological factors related to the extent of axillary lymph node (ALN) involvement in early-stage BC patients with positive sentinel lymph nodes (SLNs). Methods This was a retrospective analysis of 566 patients in cT1-2N0M0 with 1-2 positive SLNs that underwent axillary lymph node dissection (ALND) at Sun Yat-Sen Memorial Hospital. The clinical and pathologic data from these patients were analyzed. Results Of these 566 patients, 235 (41.5%) exhibited NSLN metastases. Multivariate analysis revealed that the number of positive SLNs (odds ratio (OR) = 1.511; P=0.038), the ratio of metastatic/dissected SLNs (SLN metastasis rate) (OR = 2.124; P < 0.001), and lymphovascular invasion (LVI) (OR = 1.503; P=0.022) were all independent predictors of NSLN metastasis. Patients with 0, 1, 2, or 3 of these risk factors exhibited NSLN metastases in 29.3%, 35.7%, 50.8%, and 68.3% of cases, respectively. We additionally found that the number of positive SLNs (OR = 3.582; P < 0.001), SLN metastasis rate (OR = 2.505; P=0.001), LVI (OR = 2.010; P=0.004), and HER2 overexpression (OR = 1.774; P=0.034) were all independent predictors of N2 disease. When individuals had 0, 1, 2, 3, or 4 of these risk factors, they had four or more involved ALNs in 5.2%, 10.8%, 21.1%, 37.5%, and 70.6% of cases, respectively. Conclusion These results suggest that the number of positive SLNs, the SLN metastasis rate, and LVI are all significant predictors of ALN status in BC patients that have 1-2 positive SLNs and that have undergone ALND. In addition, HER2 overexpression was a significant predictor of N2 disease.