ERBB2 and breast cancer: Some studies found no survival differences comparing patients with ERBB2-low tumors with patients with ERBB2-negative tumors,14,15,16,17,18,19,20,21,22 while others found ERBB2-low to be significant in RFS, BCSM, and OS.23,24,25,26,27,28,29 However, in several meta-analyses, significant differences were present in clinical outcomes between ERBB2-low and ERBB2-negative tumors.30,31,32,33,34,35 We found significant OS benefit associated with ERBB2-low compared with ERBB2-negative in the hormone receptor–negative BC group (ie, TNBC).