The results showed that patients with increased Slug expression in breast cancer tended to have a higher TNM stage (I–II vs III–IV; combined OR = 0.42; 95% CI = 0.25–0.70; P = 0.001) and were more prone to axillary lymph node metastasis (N+ vs N0; combined OR = 2.16; 95% CI = 1.31–3.56; P = 0.003). This evidence concerns the gene SNAI2 and metastatic malignant neoplasm in the lymph nodes.