ERBB2 and breast cancer: As seen in Figs. 5 and 6, the proportion of patients with a given stage/grade differs significantly among signature groups in luminal BC (Chi-square p = 0.0067 and p = 1.6 × 10−11, respectively) but not in HER2 BC (Chi-square p = 1 and p = 0.18, respectively) or TNBC (Chi-square p = 0.56 and p = 0.39, respectively).