High CD19 gene expression was significantly associated with a lower risk to develop metastasis in all breast cancer patients: HR (95% CI) = 0.51 (0.33–0.79) and the ER+/HER2− group: HR (95% CI) = 0.26 (0.14–0.51) (Figure 4A,B). This evidence concerns the gene ERBB2 and breast cancer.