Patients with HER2+ (0.95 vs. 0.57, p = 0.004) and HER2− (1.39 vs. 0.57, p = 0.0002) breast cancer had higher serum miR-19a median levels than HDs; however, there were no significant differences between patients with HER2+ and HER2− breast cancer (Figure 2A). This evidence concerns the gene ERBB2 and breast cancer.