Analysis of factors related to N2- or N3-stage breast cancer associated with 1-2 positive sentinel lymph nodes in Chinese patients.

Background: This study aims to determine the incidence of N2- or N3-stage disease in a cohort of patients with T1-T2 invasive breast cancer and one or two positive sentinel lymph nodes (SLNs), and identify the risk factors for N2/3 disease in this cohort.

Methods: The present study involved 298 patients with T1-T2 tumors who underwent SLN biopsy and were found to have one or two metastatic SLNs. The proportion of patients with N2/3 disease was calculated in the whole cohort, and in the T1 and T2 subgroups. Furthermore, univariate and multivariate analyses were used to identify the risk factors for N2/3 disease in the cohort.

Results: The final N stage, as determined by the postoperative pathological examination, was N1 for 250 (83.9%) patients, and N2 or N3 for 48 (16.1%) patients (11.41% had clinical N2 disease, while 4.70% had clinical N3 disease). Among the 156 patients with T1 tumors, 17 (10.9%) patients had N2/3 disease, while for the 142 patients with T2 tumors, 31 (21.8%) patients had N2/3 disease. T2 stage, lymphovascular invasion, and the number of positive SLNs were independent predictors of N2/3 disease in the cohort (P<0.05).

Conclusions: N2/3 lymph node metastasis occurs in patients with T1-T2 breast cancer, and one or two positive SLNs, particularly in patients with T2 tumors. The rate of N2/3 disease is not negligible. T2 stage, lymphovascular invasion, and the number of positive SLNs were independent predictors of N2/3 disease in the present patient population.