The HR adjusted for baseline characteristics selected by univariate analysis (age, ECOG PS, ER, HER2, bone metastasis, liver metastasis, No. of organs involved, previous therapy [endocrine, anthracycline, and taxane], RFI, and preoperative stage) was 1.00 (95% CI 0.67–1.50; p = 0.994; Table 3). This evidence concerns the gene ESR1 and bone metastasis.