Table 2.
Cox proportional hazards regression model analysis of overall survival and breast cancer-specific survival of initial metastatic breast cancer patients.
| OS | BCSS | |||||||
| Univariate analysis | Multivariate analysis | Univariate analysis | Multivariate analysis | |||||
| HR (95% CI) | P | HR | P | HR | P | HR | P | |
| Age, y | ||||||||
| <40 | Reference | Reference | Reference | Reference | ||||
| 40–70 | 1.503 (1.354–1.668) | <.001 | 1.434 (1.291–1.594) | <.001 | 1.483 (1.328–1.656) | <.001 | 1.432 (1.281–1.601) | <.001 |
| ≥70 | 2.396 (2.151–2.668) | <.001 | 2.175 (1.943–2.435) | <.001 | 2.214 (1.975–2.482) | <.001 | 2.063 (1.830–2.326) | <.001 |
| Race | ||||||||
| White | Reference | Reference | Reference | Reference | ||||
| Black | 1.282 (1.211–1.358) | <.001 | 1.185 (1.117–1.257) | <.001 | 1.271 (1.194–1.352) | <.001 | 1.158 (1.086–1.234) | <.001 |
| Others | 0.880 (0.804–0.963) | .005 | 0.958 (0.875–1.049) | .352 | 0.887 (0.805–0.976) | .014 | 0.951 (0.863–1.047) | .306 |
| Year of diagnosis | ||||||||
| 2010 | Reference | Reference | ||||||
| 2011 | 0.962 (0.900–1.029) | .260 | 0.970 (0.903–1.043) | .410 | ||||
| 2012 | 0.938 (0.874–1.007) | .075 | 0.974 (0.878–1.021) | .157 | ||||
| 2013 | 0.958 (0.890–1.031) | .251 | 0.958 (0.885–1.037) | .286 | ||||
| 2014 | 0.964 (0.888–1.046) | .378 | 0.944 (0.864–1.032) | .204 | ||||
| 2015 | 0.846 (0.760–0.941) | .002 | 0.856 (0.762–0.961) | .009 | ||||
| Grade | ||||||||
| I | Reference | Reference | Reference | Reference | ||||
| II | 1.202 (1.071–1.349) | .002 | 1.222 (1.089–1.372) | .001 | 1.297 (1.141–1.474) | <.001 | 1.310 (1.152–1.489) | <.001 |
| III/IV | 1.729 (1.545–1.935) | <.001 | 1.684 (1.499–1.892) | <.001 | 1.930 (1.703–2.186) | <.001 | 1.866 (1.641–2.122) | <.001 |
| Laterality | ||||||||
| Right | Reference | Reference | Reference | Reference | ||||
| Left | 1.013 (0.967–1.061) | .579 | 1.003 (0.958–1.050) | .902 | 1.019 (0.969–1.070) | .465 | 1.008 (0.959–1.059) | .757 |
| Bilateral | 1.520 (1.187–1.946) | .001 | 1.040 (0.811–1.334) | .758 | 1.445 (1.010–1.896) | .008 | 1.012 (0.770–1.330) | .933 |
| Lymph node metastasis | ||||||||
| N0 | Reference | Reference | Reference | Reference | ||||
| N1 | 0.863 (0.810–0.920) | <.001 | 0.899 (0.842–0.960) | .001 | 0.916 (0.855–0.981) | .013 0.930 (0.867–0.998) | 0.044 | |
| N2 | 0.842 (0.767–0.924) | <.001 | 1.026 (0.933–1.128) | .599 | 0.893 (0.809–0.986) | .026 | 1.059 (0.956–1.172) | .272 |
| N3 | 1.061 (0.994–1.133) | .074 | 1.035 (0.968–1.107) | .315 | 1.115 (1.039–1.197) | .002 | 1.054 (0.980–1.134) | .157 |
| Marital status | ||||||||
| Single | Reference | Reference | Reference | Reference | ||||
| Married | 0.759 (0.716–0.805) | <.001 | 0.804 (0.757–0.854) | <.001 | 0.768 (0.721–0.818) | <.001 | 0.816 (0.765–0.871) | <.001 |
| Others | 1.157 (1.090–1.229) | <.001 | 1.010 (0.948–1.077) | .748 | 1.137 (1.065–1.213) | <.001 | 1.016 (0.949–1.088) | .644 |
| Insurance | ||||||||
| Uninsured | Reference | Reference | Reference | Reference | ||||
| Insured | 0.751 (0.677–0.833) | <.001 | 0.788 (0.709–0.875) | <.001 | 0.739 (0.662–0.826) | <.001 | 0.787 (0.704–0.881) | <.001 |
| Surgery | ||||||||
| Surgery | Reference | Reference | Reference | Reference | ||||
| No-surgery | 1.921 (1.820–2.029) | <.001 | 1.784 (1.682–1.891) | <.001 | 1.887 (1.780–2.000) | <.001 | 1.798 (1.690–1.914) | <.001 |
| Molecular subtypes | ||||||||
| HR+/HER2+ | Reference | Reference | Reference | Reference | ||||
| HR−/HER2+ | 1.293 (1.163–1.436) | <.001 | 1.279 (1.150–1.422) | <.001 | 1.304 (1.166–1.458) | <.001 | 1.284 (1.148–1.437) | <.001 |
| HR+/HER2− | 1.223 (1.137–1.315) | <.001 | 1.309 (1.215–1.410) | <.001 | 1.194 (1.105–1.290) | <.001 | 1.309 (1.209–1.417) | <.001 |
| Triple Negative | 2.924 (2.683–3.186) | <.001 | 2.931 (2.686–3.199) | .009 | 2.942 (2.685–3.222) | <.001 | 2.977 (2.713–3.267) | <.001 |
| Metastasis sites | ||||||||
| Bone | Reference | Reference | Reference | Reference | ||||
| Lung | 1.383 (1.272–1.504) | <.001 | 1.114 (1.022–1.215) | .014 | 1.371 (1.252–1.502) | <.001 | 1.087 (0.990–1.194) | .080 |
| Liver | 1.371 (1.247–1.506) | <.001 | 1.423 (1.292–1.566) | <.001 | 1.370 (1.238–1.517) | <.001 | 1.386 (1.249–1.539) | <.001 |
| Brain | 2.318 (1.953–2.751) | <.001 | 1.904 (1.602–2.263) | <.001 | 2.340 (1.945–2.816) | <.001 | 1.904 (1.579–2.295) | <.001 |
| ≥2 Sites | 1.945 (1.841–2.054) | <.001 | 1.742 (1.646–1.843) | <.001 | 2.029 (1.914–2.152) | <.001 | 1.792 (1.686–1.904) | <.001 |
BCSS = breast cancer-specific survival, CI = confidence interval, HER2 = human epidermal growth factor receptor 2, HR = hormone receptor, OS = overall survival.