ERBB2 and breast cancer: For 390 patients with ER-positive Her2-negative BC, in multivariate analysis, DFS was significantly associated only with omission of cALND (HR: 2.358, CI 95% 1.027–5.414, p = 0.043), OS was significantly associated with omission of cALND (HR: 3.317, CI 95% 1.054–10.439, p = 0.040) and AC (HR: 0.271, CI 95% 0.075–0.978, p = 0.046), RFS was significantly associated with omission of cALND (HR: 2.538, CI 95% 1.005–6.414, p = 0.049), NAC (HR: 8.232, CI 95% 1.223–55.409.