ERBB2 and neoplasm: With regard to the molecular subtype subgroups, we found that no matter which molecular subtype, women who did not undergo primary tumour surgery had worse survival than those who experienced primary tumour surgery (HR = 1.65, 95% CI = 1.20 to 2.28 in the HER2+/HoR+ cohort; HR = 1.68, 95% CI = 1.41 to 2.00 in the HER2−/HoR+ cohort; HR = 2.09, 95% CI = 1.40 to 3.12 in the HER2+/HoR− cohort; HR = 1.93, 95% CI = 1.55 to 2.40 in the HER2−/HoR− cohort).