Table 3.
Univariate and multivariate competing risk analyses of vertebral compression fracture after SRS in spinal metastasis
| Characteristic | No. of regions | No. of events (%) | Univariatea) |
Multivariateb) |
||||
|---|---|---|---|---|---|---|---|---|
| SHR | 95% CI | p-value | SHR | 95% CI | p-value | |||
| Age (yr) | ||||||||
| ≤ 55 | 50 | 2 (4) | Reference | Reference | ||||
| > 55 | 99 | 9 (9) | 2.616 | 0.586-11.684 | 0.208 | 1.595 | 0.268-9.479 | 0.608 |
| Sex | ||||||||
| Male | 90 | 9 (10) | Reference | |||||
| Female | 59 | 2 (3) | 0.344 | 0.074-1.605 | 0.175 | NA | ||
| ECOG performance status | ||||||||
| 0-1 | 137 | 9 (7) | Reference | |||||
| 2-4 | 12 | 2 (17) | 2.902 | 0.617-13.649 | 0.177 | NA | ||
| Primary tumor | ||||||||
| Lung | 32 | 1 (3) | Reference | Reference | ||||
| Breast | 25 | 0 | 0.000 | NA | < 0.001 | 0.000 | NA | <0.001 |
| HCC | 33 | 4 (12) | 4.029 | 0.456-35.608 | 0.210 | 4.369 | 0.372-51.299 | 0.241 |
| RCC | 10 | 1 (10) | 3.619 | 0.233-56.192 | 0.358 | 2.585 | 0.095-70.547 | 0.573 |
| Others | 49 | 5 (10) | 3.548 | 0.427-29.471 | 0.241 | 4.111 | 0.470-35.958 | 0.201 |
| Solitary metastasis | ||||||||
| No | 129 | 10 (8) | Reference | |||||
| Yes | 20 | 1 (5) | 0.619 | 0.078-4.910 | 0.649 | NA | ||
| SINS criteria | ||||||||
| Tumor location | ||||||||
| Junctional (occiput-C2, C7-T2, T11-L1, L5-S1) | 58 | 5 (9) | Reference | |||||
| Mobile spine (C3-C6, L2-L4) | 44 | 3 (7) | 0.791 | 0.190-3.293 | 0.747 | NA | ||
| Semi-rigid (T3-T10) | 47 | 3 (6) | 0.775 | 0.184-3.269 | 0.728 | |||
| Pain | ||||||||
| Pain-free lesion | 38 | 1 (3) | Reference | Reference | ||||
| Occasional pain but not mechanical | 78 | 7 (9) | 3.829 | 0.475-30.813 | 0.207 | 11.769 | 0.866-159.715 | 0.064 |
| Mechanical | 33 | 3 (8) | 4.035 | 0.418-38.937 | 0.228 | 5.370 | 0.518-55.718 | 0.159 |
| Bone lesion quality | ||||||||
| Lytic | 102 | 8 (8) | Reference | Reference | ||||
| Mixed (lytic/blastic) | 30 | 2 (7) | 0.923 | 0.191-4.464 | 0.921 | 0.769 | 0.099-5.970 | 0.801 |
| Blastic | 17 | 1 (6) | 0.615 | 0.084-4.493 | 0.632 | 0.742 | 0.099-5.548 | 0.771 |
| Radiographic spinal alignment | ||||||||
| Normal alignment | 143 | 10 (7) | Reference | Reference | ||||
| Kyphosis/Scoliosis | 5 | 1 (20) | 2.760 | 0.348-21.841 | 0.336 | 8.749 | 1.069-71.643 | 0.043 |
| Subluxation/Translation | 1 | 0 | 0.000 | NA | < 0.001 | 0.000 | NA | < 0.001 |
| Vertebral body fracture | ||||||||
| None of the below | 85 | 5 (6) | Reference | |||||
| No collapse with > 50% body involved | 28 | 2 (7) | 1.224 | 0.240-6.247 | 0.808 | NA | ||
| < 50% collapse | 28 | 3 (11) | 2.115 | 0.504-8.869 | 0.306 | |||
| > 50% collapse | 8 | 1 (13) | 2.107 | 0.272-16.221 | 0.477 | |||
| Posterolateral involvement of spinal elements | ||||||||
| None of the above | 83 | 6 (7) | Reference | Reference | ||||
| Unilateral | 44 | 4 (9) | 1.393 | 0.397-4.887 | 0.604 | 0.842 | 0.141-5.019 | 0.850 |
| Bilateral | 22 | 1 (5) | 0.616 | 0.074-5.157 | 0.655 | 0.190 | 0.025-1.453 | 0.109 |
| SINS classification | ||||||||
| Stability | 83 | 6 (7) | Reference | |||||
| Intermediate stability | 62 | 4 (6) | 0.964 | 0.275-3.371 | 0.954 | NA | ||
| Instability | 4 | 1 (25) | 3.491 | 0.414-29.456 | 0.251 | |||
| SRS dose (Gy) | ||||||||
| ≤ 20 | 135 | 10 (7) | Reference | Reference | ||||
| > 20 | 14 | 1 (7) | 1.065 | 0.136-9.332 | 0.952 | 1.934 | 0.172-21.749 | 0.593 |
| ISRC sites number of treatment field | ||||||||
| 1-3 | 62 | 5 (8) | Reference | Reference | ||||
| 4-6 | 87 | 6 (7) | 0.838 | 0.256-2.739 | 0.770 | 0.807 | 0.098-6.628 | 0.807 |
| Bilsky | ||||||||
| Grade 0 | 80 | 5 (6) | Reference | Reference | ||||
| Grade 1 | 39 | 2 (5) | 0.781 | 0.154-3.962 | 0.766 | 0.753 | 0.150-3.780 | 0.730 |
| Grade 2 | 21 | 3 (14) | 2.733 | 0.635-11.767 | 0.177 | 5.368 | 1.129-25.530 | 0.035 |
| Grade 3 | 9 | 1 (11) | 1.890 | 0.224-15.934 | 0.559 | 2.215 | 0.269-18.248 | 0.460 |
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.