Our analysis of the relation between HRG gene expression and clinical outcome in women with HER2+ breast cancer (n = 204) revealed a linear correlation between HRG expression and risk of recurrence (P = 0.0036, Cox-regression analysis) and a statistically significant difference (P = 0.0034, Kaplan-Meier Estimates survival analysis) between high HRG expression and decreased recurrence-free survival (RFS) (Figure 8). This evidence concerns the gene ERBB2 and breast cancer.