Table 2.
Univariate and multivariate Cox proportional hazards model of overall survival
| Variables | Univariate | Multivariate | ||
|---|---|---|---|---|
| HR (95% CI) | P‐value | HR (95% CI) | P‐value | |
| Number of BM treated | ||||
| 2–4 | Ref. | Ref. | Ref. | Ref. |
| 5+ | 1.396 (1.062–1.810) | 0.0176 | 1.220 (0.903–1.624) | 0.1921 |
| Age | ||||
| ≤60 years | Ref. | Ref. | Ref. | Ref. |
| >60 years | 1.228 (0.991–1.521) | 0.0604 | 1.201 (0.957–1.505) | 0.1143 |
| Sex | ||||
| Male | Ref. | Ref. | – | – |
| Female | 0.877 | 0.2272 | – | – |
| Histology | ||||
| Breast adenocarcinoma | Ref. | Ref. | Ref. | Ref. |
| Lung NSCLC | 1.557 (1.059–2.291) | 0.0236 | 1.664 (1.110–2.497) | 0.0134 |
| Melanoma | 1.473 (1.059–2.049) | 0.0173 | 1.422 (0.997–2.009) | 0.0397 |
| Renal cell carcinoma | 1.180 (0.725–1.922) | 0.5085 | 1.053 (0.641–1.730) | 0.8395 |
| Other | 2.463 (1.596–3.800) | <0.0001 | 1.947 (1.231–3.079) | 0.0049 |
| KPS | ||||
| 90–100 | Ref. | Ref. | Ref. | Ref. |
| 70–80 | 1.533 (1.219–1.922) | 0.0003 | 1.417 (1.111–1.802) | 0.0052 |
| ≤60 | 2.690 (1.542–4.369) | 0.0010 | 2.340 (1.301–3.912) | 0.0059 |
| GPA | ||||
| 0–1 | Ref. | Ref. | – | – |
| 1.5–2.5 | 0.686 (0.537–0.883) | 0.0037 | – | – |
| 3–4 | 0.514 (0.330–0.777) | 0.0013 | – | – |
| RPA | ||||
| Class 1 | Ref. | Ref. | – | – |
| Class 2 | 1.129 (0.827–1.579) | 0.4546 | – | – |
| Class 3 | 2.394 (1.305–4.177) | 0.0059 | – | – |
| Synchronous BM | 1.139 (0.815–1.556) | 0.4351 | – | – |
| Increase in number of BM from baseline to treatment | 0.908 (0.725–1.131) | 0.3911 | – | – |
| Untreated BM | 1.436 (1.078–1.882) | 0.0142 | 1.321 (0.977–1.757) | 0.0701 |
| Infratentorial BM | 1.140 (0.915–1.415) | 0.2418 | – | – |
| SRS dose | 0.961 (0.915–1.013) | 0.1394 | – | – |
| SRS dose | ||||
| <18 Gy | Ref. | Ref. | – | – |
| ≥18 Gy | 1.141 (0.870–1.477) | 0.3323 | – | – |
| Total tumor volume | ||||
| <5 ccs | Ref. | Ref. | Ref. | Ref. |
| 5–10 ccs | 1.223 (0.916–1.610) | 0.1682 | 1.326 (0.979–1.768) | 0.0678 |
| >10 ccs | 1.451 (1.094–1.900) | 0.0103 | 1.641 (1.217–2.186) | 0.0014 |
NSCLC, Nonsmall Cell Lung Cancer; KPS, Karnofsky Performance Status; GPA, Grade Prognostic Assessment; RPA, Recursive Partitioning Analysis; mets, metastases; SRS, Stereotactic Radiosurgery.