ERBB2 and breast cancer: In DFS, RPCB class I in hormone receptor+HER2− BC had an HR of 6.38 (95% CI: 1.14, 28.91), 13.71 in class II (95% CI: 3.06, 61.42), and 36.75 in class III (95% CI: 7.91, 170.67) compared with RCB 0 (p <0.001) (Figure 3A).