Table 2. Cox Proportional Hazard Multivariable Analysis Results for Entire Study.
| Covariate | Comparison | Overall Survival | Disease-Free Survival | Brain Metastasis | |||
|---|---|---|---|---|---|---|---|
| HR (95% CI) | P Value | HR (95% CI) | P Value | HR (95% CI) | P Value | ||
| Treatment arm | PCI | 0.84 (0.66-1.07) | .16 | 0.78 (0.62-0.99) | .04 | 0.44 (0.25-0.77 | .01 |
| Observation (RL) | 1 [Reference] | ||||||
| Age | ≥60 years | 1.39 (1.08-1.79) | .01 | 1.14 (0.90 1.45 | .29 | 0.57 (0.34-0.97) | .04 |
| <60 years | 1 [Reference] | ||||||
| Zubrod | >0 | 1.34 (1.05-1.72) | .02 | 1.18 (0.93-1.49) | .17 | 1.00 (0.59-1.70) | .99 |
| 0 | 1 [Reference] | ||||||
| Prior surgery | Yes | 0.82 (0.62-1.07) | .14 | 0.79 (0.61-1.02) | .07 | 0.65 (0.36-1.19) | .16 |
| No | 1 [Reference] | ||||||
| AJCC stage | IIIB | 1.17 (0.91-1.50) | .22 | 1.23 (0.96-1.56) | .10 | 0.88 (0.51-1.54) | .65 |
| IIIA | 1 [Reference] | ||||||
| Histologic characteristics | Squamous | 1.08 (0.84-1.39) | .56 | 1.01 (0.80-1.29) | .91 | 0.20 (0.08-0.46) | .01 |
| Nonsquamous | 1 [Reference] | ||||||
Abbreviations: AJCC, American Joint Committee on Cancer; HR, hazard ratio; PCI, prophylactic cranial irradiation.