ERBB2 and breast cancer: In HER2-positive breast cancer, clinical N stage (p=0.009), histologic grade (p<0.001), ER expression status (p=0.001), PR expression status (p<0.001), HER2 expression status (p=0.001), presence of lymphovascular invasion (p = 0.002), NAT regimens incorporating dual-targeted therapy (p=0.029) or anthracycline-based combinations (p=0.036), and postoperative pCR in the primary breast tumor (p < 0.001) were significantly associated with achieving ypN0 following NAT (Table 3).