ERBB2 and breast cancer: In the training set, the medians of Rad-score showed a statistical difference between the HER2+ and HER2− BC (0.0838 vs. −0.0546, p < 0.001), and the same results were achieved in the validation set (0.0936 vs. −0.0518, p < 0.001) (Figure 6C,D, Table 3).