ERBB2 and breast cancer: The HER2DX pCR score remained the only independent predictor of pCR in multivariable analysis (OR, 1.77; 95% confidence interval, 1.08-2.97; P = 0.030).<h4>Conclusions</h4>HER2DX reflects key biological and pathologic features of HER2+ breast cancer and independently predicts pCR, supporting its utility for individualized treatment decision-making.