Table 2.
Gray’s test and Fine–Gray proportional subdistribution hazard method analysis of breast cancer-specific survival (BCSS) and multivariable cox regression analyses of overall survival (OS) for patients with metastatic breast cancer.
| Characteristic (n) | Univariable analysis | Multivariable analysis | ||
|---|---|---|---|---|
| Gray’s test | p-value | SHR (95% CI) | p-value | |
| BCSS | ||||
| Marital status | 113.425 | < 0.001 | < 0.001 | |
| Unmarried (8949) | Reference | |||
| Married (7564) | 0.845 (0.804–0.888) | |||
| Ages | 15.267 | < 0.001 | 0.551 | |
| < 65 (9811) | Reference | |||
| ≥ 65 (6702) | 1.016 (0.964–1.072) | |||
| Race | 74.555 | < 0.001 | < 0.001 | |
| White (12,407) | Reference | |||
| Black (2764) | 1.164 (1.092–1.242) | < 0.001 | ||
| Other (1296) | 0.979 (0.893–1.073) | 0.647 | ||
| Unknown (46) | 0.421 (0.194–0.914) | 0.029 | ||
| Grade | 248.417 | < 0.001 | < 0.001 | |
| I (1170) | Reference | |||
| II (6017) | 1.332 (1.195–1.485) | < 0.001 | ||
| III (6755) | 1.798 (1.610–2.009) | < 0.001 | ||
| IV (99) | 2.029 (1.500–2.745) | < 0.001 | ||
| Unknown (2472) | 1.479 (1.311–1.668) | < 0.001 | ||
| Subtype | 620.687 | < 0.001 | < 0.001 | |
| HR(–) & HER2(–) (2018) | Reference | |||
| HR(–) & HER2( +) (1306) | 0.499 (0.447–0.557) | < 0.001 | ||
| HR( +) & HER2(–) (9201) | 0.493 (0.455–0.533) | < 0.001 | ||
| HR( +) & HER2( +) (2489) | 0.416 (0.379–0.456) | < 0.001 | ||
| Unknown (1499) | 0.561 (0.503–0.627) | < 0.001 | ||
| Chemotherapy | 79.255 | < 0.001 | < 0.001 | |
| No (7465) | Reference | |||
| Yes (9048) | 0.845 (0.798–0.895) | |||
| Radiation | 17.511 | < 0.001 | NI | |
| No (10,937) | ||||
| Yes (5207) | ||||
| Unknown (369) | ||||
| Surgery | 440.224 | < 0.001 | < 0.001 | |
| No surgery (10,951) | Reference | |||
| Partial mastectomy (1554) | 0.634 (0.579–0.694) | < 0.001 | ||
| Simple mastectomy (1308) | 0.587 (0.531–0.649) | < 0.001 | ||
| Radical mastectomy (2542) | 0.740 (0.691–0.793) | < 0.001 | ||
| Unknown (158) | 1.025 (0.826–1.273) | 0.820 | ||
| Distant organ metastasis | 685.312 | < 0.001 | < 0.001 | |
| No (1990) | Reference | |||
| One site (9374) | 1.249 (1.149–1.358) | < 0.001 | ||
| Multiple sites (4959) | 1.927 (1.763–2.105) | < 0.001 | ||
| Unknown (190) | 1.331 (1.057–1.677) | 0.015 | ||
| OS | HR (95% CI) | p-value | HR (95% CI) | p-value |
|---|---|---|---|---|
| Marital status | < 0.001 | < 0.001 | ||
| Unmarried (8494) | Reference | Reference | ||
| Married (7564) | 0.695 (0.668–0.723) | 0.810(0.777–0.844) | ||
| Ages | < 0.001 | < 0.001 | ||
| < 65 (9811) | Reference | Reference | ||
| ≥ 65 (6702) | 1.514 (1.456–1.575) | 1.360 (1.304–1.418) | ||
| Race | < 0.001 | < 0.001 | ||
| White (12,407) | Reference | Reference | ||
| Black (2764) | 1.318 (1.253–1.386) | < 0.001 | 1.236 (1.174–1.302) | < 0.001 |
| Other (1296) | 0.930 (0.861–1.004) | 0.064 | 0.986 (0.912–1.065) | 0.717 |
| Unknown (46) | 0.459 (0.254–0.828) | 0.010 | 0.408 (0.226–0.736) | 0.003 |
| Grade | < 0.001 | < 0.001 | ||
| I (1170) | Reference | Reference | ||
| II (6017) | 1.253 (1.146–1.370) | < 0.001 | 1.275 (1.166–1.394) | < 0.001 |
| III (6755) | 1.664 (1.525–1.816) | < 0.001 | 1.722 (1.573–1.885) | < 0.001 |
| IV (99) | 1.790 (1.398–2.290) | < 0.001 | 2.008 (1.567–2.573) | < 0.001 |
| Unknown (2472) | 1.723 (1.567–1.896) | < 0.001 | 1.493 (1.355–1.644) | < 0.001 |
| Subtype | < 0.001 | < 0.001 | ||
| HR(–) & HER2(–) (2018) | Reference | Reference | ||
| HR(–) & HER2( +) (1306) | 0.412 (0.377–0.450) | < 0.001 | 0.404 (0.370–0.442) | < 0.001 |
| HR( +) & HER2(–) (9201) | 0.420 (0.397–0.444) | < 0.001 | 0.356 (0.335–0.379) | < 0.001 |
| HR( +) & HER2( +) (2489) | 0.332 (0.308–0.358) | < 0.001 | 0.308 (0.285–0.332) | < 0.001 |
| Unknown (1499) | 0.638 (0.591–0.689) | < 0.001 | 0.503 (0.464–0.546) | < 0.001 |
| Chemotherapy | < 0.001 | < 0.001 | ||
| No (7465) | Reference | Reference | ||
| Yes (9048) | 0.664 (0.638–0.690) | 0.642 (0.614–0.672) | ||
| Radiation | < 0.001 | 0.005 | ||
| No (10,937) | Reference | |||
| Yes (5207) | 0.813 (0.779–0.849) | < 0.001 | 0.946 (0.905–0.988) | 0.012 |
| Unknown (369) | 0.633 (0.545–0.736) | < 0.001 | 0.834 (0.718–0.970) | 0.018 |
| Surgery | < 0.001 | < 0.001 | ||
| No surgery (10,951) | Reference | Reference | ||
| Partial mastectomy (1554) | 0.543 (0.504–0.585) | < 0.001 | 0.586 (0.543–0.633) | < 0.001 |
| Simple mastectomy (1308) | 0.522 (0.481–0.566) | < 0.001 | 0.565 (0.521–0.614) | < 0.001 |
| Radical mastectomy (2542) | 0.560 (0.528–0.594) | < 0.001 | 0.640 (0.602–0.681) | < 0.001 |
| Unknown (158) | 0.840 (0.688–1.026) | 0.087 | 0.842 (0.689–1.028) | 0.091 |
| Distant organ metastasis | < 0.001 | < 0.001 | ||
| No (1990) | Reference | Reference | ||
| One site (9374) | 1.135 (1.062–1.213) | < 0.001 | 1.122 (1.050–1.200) | 0.001 |
| Multiple sites (4959) | 1.924 (1.796–2.061) | < 0.001 | 1.860 (1.733–1.995) | < 0.001 |
| Unknown (190) | 1.543 (1.291–1.845) | < 0.001 | 1.373 (1.148–1.643) | 0.001 |
Distant organ metastasis only included bone, liver, lung, and brain metastases in the SEER database (2010–2015). Patients with an unknown cause of death were classified as dying of a non-tumor-related cause. There were 7389 deaths from tumors, 2614 deaths from other causes, and 6510 survivors at the follow-up endpoint.
NI: The competing risk analysis in Stata software was performed using the “stcrreg” command, where NI refers to the variable being excluded from the multivariable analysis model. SHR subdistribution hazard ratio.