Table 1.
Baseline characteristics
| Characteristic | n | % or range | Grade ≥2 late toxicity |
Vertebral compression fracture |
||||
|---|---|---|---|---|---|---|---|---|
| No (%) | Yes (%) | HR (95% CI) | No (%) | Yes (%) | HR (95% CI) | |||
| Age (y) | ||||||||
| <60 | 32 | 59.3 | 84.4 | 15.6 | 81.3 | 18.8 | ||
| ≥60 | 22 | 40.7 | 81.8 | 18.2 | 1.2 (0.3–5.1) | 86.4 | 13.6 | 0.5 (0.1-2.6) |
| Sex | ||||||||
| Male | 23 | 42.6 | 82.6 | 17.4 | 87.0 | 13.0 | ||
| Female | 31 | 57.4 | 83.9 | 16.1 | 0.9 (0.2-3.9) | 80.6 | 19.4 | 1.3 (0.3-6.2) |
| Primary tumor histology | ||||||||
| Breast | 22 | 40.7 | 77.3 | 22.7 | 86.4 | 13.6 | ||
| Renal | 11 | 20.4 | 81.8 | 18.2 | 0.8 (0.1-4.7) | 81.8 | 18.2 | 1.4 (0.2-10.0) |
| NSCLC | 5 | 9.3 | 100.0 | 0.0 | - | 100.0 | 0.0 | - |
| Other | 16 | 29.6 | 87.5 | 12.5 | 0.5 (0.1-2.9) | 75.0 | 25.0 | 1.9 (0.3-11.2) |
| Level treated | ||||||||
| Cervical | 9 | 16.7 | 88.9 | 11.1 | 88.9 | 11.1 | ||
| Thoracic | 24 | 44.4 | 87.5 | 12.5 | 1.1 (0.1-12.7) | 83.3 | 16.7 | - |
| Lumbar | 13 | 24.1 | 100.0 | 0.0 | - | 76.9 | 23.1 | - |
| Sacral | 8 | 14.8 | 37.5 | 62.5 | 13.3 (1.1-166.4) | 87.5 | 12.5 | - |
| Prior EBRT | 30 | 55.6 | - | - | - | - | - | - |
| Median reirradiation interval after EBRT (mo) | 12.7 | 0.9-145.0 | - | - | - | - | - | - |
| Median prior EBRT BED3 (Gy) | 60 | 27-131 | - | - | - | - | - | - |
| Lesion type | ||||||||
| Sclerotic | 9 | 16.7 | - | - | - | 77.8 | 22.2 | |
| Lytic | 23 | 42.6 | - | - | - | 82.6 | 17.4 | 0.4 (0.1-2.2) |
| Mixed | 7 | 13.0 | 100.0 | 0.0 | ||||
| Pre-existing fracture | ||||||||
| No | 45 | 83.3 | - | - | - | 84.4 | 15.6 | |
| Yes | 9 | 16.7 | - | - | - | 77.8 | 22.2 | 1.7 (0.3-10.3) |
| Single-fraction SRS dose (Gy) | - | - | - | |||||
| ≤16 | 38 | 56.7 | - | - | - | 86.8 | 13.2 | |
| >16 | 29 | 43.3 | - | - | - | 86.2 | 13.8 | 1.1 (0.3-4.3) |
| Cumulative BED3 (Gy) | ||||||||
| <200 | 31 | 57.4 | 96.8 | 3.2 | 83.9 | 16.1 | ||
| ≥200 | 23 | 42.6 | 65.2 | 34.8 | 16.0 (1.8-140.0) | 82.6 | 17.4 | 1.3 (0.3-5.7) |
Abbreviations: BED = biologically equivalent dose; CI = confidence interval; EBRT = external beam radiation therapy; HR = hazard ratio; NSCLC = non–small cell lung cancer.