ERBB2 and breast cancer: Based on univariate analysis, there were significant differences in stage_N (P = 0.029), histological grade (P = 0.003), ER (P < 0.001), PgR (P = 0.047), Ki-67 (P < 0.001) and HER2 status (P = 0.015) for achieving a pCR in patients with ER-positive breast cancer.