TABLE 2.
Comparison of Baseline Characteristics by Primary (No Prior WBRT) vs Salvage SRS (Prior WBRT)
| SRS alone (n = 61) | SRS + prior WBRT (n = 232) | Odds ratio | 95% CI | P value | |
|---|---|---|---|---|---|
| Age | |||||
| ≤63 yr | 21 (34%) | 133 (57%) | 1 | Reference | |
| >63 yr | 40 (66%) | 99 (43%) | 0.39 | 0.22-0.70 | .002 |
| Gender (n = 285) | |||||
| Female | 24 (41%) | 120 (53%) | 1 | Reference | |
| Male | 34 (59%) | 107 (47%) | 0.63 | 0.35-1.13 | .12 |
| Time to brain metastases | |||||
| Metachronous | 26 (43%) | 153 (66%) | 1 | Reference | |
| Synchronous | 35 (57%) | 79 (34%) | 0.38 | 0.21-0.68 | .001 |
| SRS mean marginal dose (n = 244) | |||||
| ≤18.0 Gy | 35 (61%) | 129 (69%) | 1 | Reference | |
| >18.0 Gy | 22 (39%) | 58 (31%) | 1.40 | 0.76-2.59 | .29 |
| Volume of metastases (n = 251) | |||||
| ≤3.3 cc | 26 (50%) | 103 (52%) | 1 | Reference | |
| >3.3 cc | 26 (50%) | 96 (48%) | 0.93 | 0.51-1.72 | .82 |
| Number of metastases | |||||
| ≤2 | 39 (64%) | 115 (50%) | 1 | Reference | |
| >2 | 22 (36%) | 117 (50%) | 1.80 | 1.01-3.23 | .05 |