Table 2.
Univariate and multivariate competing risk analyses of local progression after SRS in spinal metastasis
| Characteristic | No. of regions | No. of events (%) | Univariate |
Multivariate |
||||
|---|---|---|---|---|---|---|---|---|
| SHR | 95% CI | p-valuea) | SHR | 95% CI | p-valueb) | |||
| Age (yr) | ||||||||
| ≤ 55 | 50 | 1 (2) | Reference | Reference | ||||
| > 55 | 99 | 6 (6) | 3.409 | 0.430-27.026 | 0.246 | 1.744 | 0.256-11.843 | 0.569 |
| Sex | ||||||||
| Male | 90 | 6 (7) | Reference | |||||
| Female | 59 | 1 (2) | 0.257 | 0.0316-2.095 | 0.204 | NA | ||
| ECOG performance status | ||||||||
| 0-1 | 137 | 6 (4) | Reference | |||||
| 2-4 | 12 | 1 (8) | 1.939 | 0.230-16.366 | 0.543 | NA | ||
| Primary tumor | ||||||||
| Lung | 32 | 1 (3) | Reference | Reference | ||||
| Breast | 25 | 0 | 0.000 | NA | < 0.001 | 0.000 | NA | < 0.001 |
| HCC | 33 | 2 (6) | 1.900 | 0.180-19.976 | 0.594 | 3.526 | 0.388-32.061 | 0.263 |
| RCC | 10 | 2 (20) | 7.885 | 0.783-79.411 | 0.080 | 5.002 | 1.028-24.341 | 0.046 |
| Others | 49 | 2 (4) | 1.362 | 0.130-14.333 | 0.797 | 1.490 | 0.103-21.624 | 0.770 |
| Solitary metastasis | ||||||||
| No | 129 | 7 (5) | Reference | Reference | ||||
| Yes | 20 | 0 | 0.000 | NA | < 0.001 | 0.000 | NA | < 0.001 |
| SINS criteria | ||||||||
| Tumor location | ||||||||
| Junctional (occiput-C2, C7-T2, T11-L1, L5-S1) | 58 | 4 (7) | Reference | |||||
| Mobile spine (C3-C6, L2-L4) | 44 | 1 (2) | 0.338 | 0.038-3.004 | 0.331 | NA | ||
| Semi-rigid (T3-T10) | 47 | 2 (4) | 0.649 | 0.121-3.496 | 0.615 | |||
| Pain | ||||||||
| Pain-free lesion | 38 | 2 (5) | Reference | |||||
| Occasional pain but not mechanical | 78 | 2 (3) | 0.526 | 0.075-3.694 | 0.518 | NA | ||
| Mechanical | 33 | 3 (9) | 1.978 | 0.337-11.620 | 0.450 | |||
| Bone lesion quality | ||||||||
| Lytic | 102 | 6 (6) | Reference | Reference | ||||
| Mixed (lytic/blastic) | 30 | 1 (3) | 0.596 | 0.072-4.962 | 0.632 | 0.236 | 0.004-15.243 | 0.497 |
| Blastic | 17 | 0 | 0.000 | NA | < 0.001 | 0.000 | NA | < 0.001 |
| Radiographic spinal alignment | ||||||||
| Normal alignment | 143 | 7 (5) | Reference | |||||
| Kyphosis/Scoliosis | 5 | 0 | 0.000 | NA | < 0.001 | NA | ||
| Subluxation/Translation | 1 | 0 | 0.000 | NA | < 0.001 | |||
| Vertebral body fracture | ||||||||
| None of the below | 85 | 3 (4) | Reference | |||||
| No collapse with > 50% body involved | 28 | 1 (4) | 1.045 | 0.107-10.186 | 0.970 | NA | ||
| < 50% collapse | 28 | 3 (11) | 3.405 | 0.706-16.421 | 0.127 | |||
| > 50% collapse | 8 | 0 | 0.000 | NA | < 0.001 | |||
| Posterolateral involvement of spinal elements | ||||||||
| None of the above | 83 | 2 (2) | Reference | Reference | ||||
| Unilateral | 44 | 3 (7) | 3.178 | 0.546-18.488 | 0.198 | 1.222 | 0.091-16.420 | 0.880 |
| Bilateral | 22 | 2 (9) | 3.827 | 0.539-27.187 | 0.180 | 1.576 | 0.208-11.909 | 0.660 |
| SINS classification | ||||||||
| Stability | 83 | 3 (4) | Reference | |||||
| Intermediate stability | 62 | 3 (5) | 1.436 | 0.293-7.043 | 0.622 | NA | ||
| Instability | 4 | 1 (25) | 7.426 | 0.702-78.505 | 0.096 | |||
| SRS dose (Gy) | ||||||||
| ≤ 20 | 135 | 7 (5) | Reference | Reference | ||||
| > 20 | 14 | 0 | 0.000 | NA | NA | 0.000 | NA | < 0.001 |
| ISRC sites number of treatment field | ||||||||
| 1-3 | 62 | 0 | Reference | Reference | ||||
| 4-6 | 87 | 7 (8) | NA | NA | NA | NA | NA | < 0.001 |
| Bilsky | ||||||||
| Grade 0 | 80 | 2 (3) | Reference | Reference | ||||
| Grade 1 | 39 | 3 (8) | 2.917 | 0.494-17.214 | 0.237 | 1.160 | 0.078-17.203 | 0.914 |
| Grade 2 | 21 | 0 | 0.000 | NA | < 0.001 | 0.000 | NA | < 0.001 |
| Grade 3 | 9 | 2 (22) | 9.493 | 1.412-63.825 | 0.021 | 4.521 | 0.353-57.852 | 0.246 |
SRS, stereotactic radiosurgery; SHR, subhazard ratio; CI, confidence interval; NA, not applicable; ECOG, Eastern Cooperative Oncology Group; HCC, hepatocellular carcinoma; RCC, renal cell carcinoma; SINS, Spinal Instability Neoplastic Score; ISRC, International Spine Radiosurgery Consortium.
a)
Univariate competing-risks regressions based on Fine and Gray’s proportional subhazards model,
b)
Multivariate competing-risks regressions based on Fine and Gray’s proportional subhazards model.