In addition, we identified several features which associated with worse survival in bone metastatic breast cancer, including older age at diagnosis (>70 years old), higher tumor grade and T staging (T3–T4), HER2 negativity, absence of surgery and chemotherapy, and more importantly, primary tumor HR status of ER-negative/PR-positive or ER-negative/PR-negative. Here, ESR1 is linked to neoplasm.