As shown in Figure 5, the identified PBMC biomarkers (TMSB4X, HSPA4, S100A9, SRSF6, THBS1, CUL4A, and CANX) were significantly upregulated in the breast cancer patients at the metastatic stage compared to both the primary stage and healthy individuals (p < 0.001). This evidence concerns the gene S100A9 and breast cancer.