ERBB2 and breast cancer: For ER-positive Her2-negative BC patients, in multivariate analysis, DFS was significantly associated only with omission of cALND (HR: 2.358, p = 0.043), OS, RFS, and MFS were significantly associated with omission of cALND (HR: 3.317, p = 0.040; HR: 2.538, p = 0.049; HR: 2.756, p = 0.014, respectively).