ERBB2 and breast cancer: There were statistically significant survival benefits with adjuvant chemotherapy in T1bN0M0 BC patients with HoR + /HER2 + (HR, 0.41; 95% CI, 0.25–0.69; P < 0.0001), HoR-/HER2 + (HR, 0.50; 95% CI, 0.25–1.02; P = 0.01), HoR-/HER2- (HR, 0.53; 95% CI, 0.36–0.78; P < 0.0001), and grade III (HR, 0.52; 95% CI, 0.38–0.70; P < 0.0001) tumors, as compared to patients that did not receive any adjuvant chemotherapy.