The results of immunohistochemistry demonstrated CXCR4 and CXCL12 co-expression in 27.4% (50/182) breast cancer samples and the co-expression of CXCR4 and CXCL12 correlated with lymph node metastasis and TNM stage (p < 0.01) (Table 2). This evidence concerns the gene CXCL12 and breast cancer.