ERBB2 and breast cancer: When both the H&E-ERBB2 score and histological grade were included in a logistic regression analysis as covariates, the H&E-ERBB2 score remained as an independent predictor of breast cancer ERBB2 status in the FinProg test set (P = 0.005) and also in the FinHer external test set (P < 0.001).