Table 2.
Univariate and multivariate analysis cancer-specific survival (CSS) of bone metastasis breast cancer (BMBC) in the training cohort.
| Characteristic | Univariate | Multivariate | ||||
| HR | 95%CI | P value | HR | 95%CI | P value | |
| Age, years | ||||||
| +1 year | 1.011 | 1.007–1.016 | <0.001 | 1.010 | 1.006–1.015 | <0.001 |
| Race | <0.001 | 0.013 | ||||
| White | 1(Ref) | 1(Ref) | ||||
| Black | 1.397 | 1.216–1.604 | <0.001 | 1.212 | 1.049–1.399 | 0.009 |
| Other | 0.977 | 0.790–1.209 | 0.601 | 0.893 | 0.720–1.108 | 0.305 |
| Marital status | ||||||
| Married | 1(Ref) | 1(Ref) | ||||
| USDW | 1.299 | 1.166–1.448 | <0.001 | 1.173 | 1.048–1.313 | 0.006 |
| T stage | <0.001 | 0.005 | ||||
| T0-T1 | 1(Ref) | 1(Ref) | ||||
| T2 | 0.937 | 0.775–1.133 | 0.503 | 0.972 | 0.802–1.179 | 0.776 |
| T3 | 1.333 | 1.088–1.633 | 0.005 | 1.217 | 0.990–1.497 | 0.062 |
| T4 | 1.544 | 1.282–1.859 | <0.001 | 1.200 | 0.990–1.453 | 0.063 |
| Clinical nodal status | ||||||
| Negative | 1(Ref) | |||||
| Positive | 1.055 | 0.922–1.207 | 0.439 | |||
| Histology | ||||||
| IDC | 1(Ref) | |||||
| ILC | 1.019 | 0.867–1.199 | 0.817 | |||
| Tumor grade | <0.001 | <0.001 | ||||
| I | 1(Ref) | 1(Ref) | ||||
| II | 1.361 | 1.073–1.726 | 0.011 | 1.392 | 1.094–1.770 | 0.007 |
| III | 1.929 | 1.522–2.444 | <0.001 | 1.905 | 1.488–2.438 | <0.001 |
| IV | 4.050 | 2.248–7.293 | <0.001 | 2.741 | 1.506–4.989 | 0.001 |
| ER | ||||||
| Negative | 1(Ref) | 1(Ref) | ||||
| Positive | 0.523 | 0.460–0.595 | <0.001 | 0.709 | 0.592–0.849 | <0.001 |
| PR | ||||||
| Negative | 1(Ref) | 1(Ref) | ||||
| Positive | 0.552 | 0.494–0.617 | <0.001 | 0.640 | 0.550–0.744 | <0.001 |
| HER2 | ||||||
| Negative | 1(Ref) | 1(Ref) | ||||
| Positive | 0.778 | 0.681–0.888 | <0.001 | 0.502 | 0.432–0.583 | <0.001 |
| Brain metastasis | ||||||
| No | 1(Ref) | 1(Ref) | ||||
| Yes | 2.437 | 2.028–2.927 | <0.001 | 1.806 | 1.492–2.187 | <0.001 |
| Liver metastasis | ||||||
| No | 1(Ref) | 1(Ref) | ||||
| Yes | 2.105 | 1.868–2.373 | <0.001 | 1.814 | 1.591–2.068 | <0.001 |
| Lung metastasis | ||||||
| No | 1(Ref) | 1(Ref) | ||||
| Yes | 1.799 | 1.601–2.022 | <0.001 | 1.355 | 1.195–1.536 | <0.001 |
| Breast surgery | <0.001 | <0.001 | ||||
| No | 1(Ref) | 1(Ref) | ||||
| Breast-conserving surgery | 0.385 | 0.313–0.474 | 0.001 | 0.458 | 0.370–0.567 | <0.001 |
| Mastectomy | 0.565 | 0.496–0.644 | <0.001 | 0.613 | 0.534–0.704 | <0.001 |
| Distant surgery | ||||||
| No | 1(Ref) | |||||
| Yes | 0.941 | 0.699–1.267 | 0.688 | |||
| Chemotherapy | ||||||
| No | 1(Ref) | 1(Ref) | ||||
| Yes | 0.897 | 0.803–1.003 | 0.055 | 0.845 | 0.745–0.959 | 0.009 |
| Radiation therapy | ||||||
| No | 1(Ref) | |||||
| Yes | 0.922 | 0.826–1.028 | 0.143 | |||
CI = confidence interval, ER = estrogen receptor, HER2 = human epidermal growth factor receptor 2, HR = hazard ratio, IDC = infiltrating ductal carcinoma, ILC = infiltrating lobular carcinoma, Other = American Indian/AK Native, Asian/Pacific Islander, PR = progesterone receptor, Radiation therapy = beam radiation for breast or anterior chest wall, Tumor grade I = well differentiated, Tumor grade II = moderately differentiated, Tumor grade III = poorly differentiated, Tumor grade IV = undifferentiated, USDW = unmarried/separated/divorced/widowed.