TABLE 4.
Univariate Cox Proportional Hazards for Overall Survival From the Time of Glioblastoma Diagnosisa
| Hazard Ratio | |||
|---|---|---|---|
| Clinical Parameter | n | (95% Confidence Interval) | P |
| Male sex (vs female) | 174 | 0.93 (0.67-1.27) | .63 |
| Gliosarcoma (vs glioblastoma) | 174 | 0.84 (0.44-1.60) | .60 |
| Age at glioblastoma diagnosis | 174 | 1.03 (1.02-1.04) | <.001 |
| Extent of first surgical resection (vs gross total resection) | |||
| Gross total | 65 | 1.00 | Referent |
| Near total | 10 | 1.18 (0.54-2.59) | .68 |
| Subtotal | 69 | 1.00 (0.70-1.41) | .98 |
| Biopsy | 19 | 1.50 (0.89-2.53) | .12 |
| Multiple pre-GK craniotomies | 174 | 0.78 (0.57-1.08) | .13 |
| Concurrent chemotherapy with initial fractionated radiotherapyb | — | — | |
| Time from initial surgery to GKb | — | — | |
| Age at GK procedure, y | |||
| Continuous variable | 174 | 1.029 (1.016-1.042) | <.001 |
| ≤45.4 | 43 | 1.00 | Referent |
| >45.4 | 131 | 2.33 (1.60-3.40) | <.001 |
| Multiple GK treatment targets (vs single lesion)b | — | — | |
| Total treatment volume, cm3 | |||
| Continuous variable | 167 | 1.02 (1.00-1.04) | .11 |
| ≤6.20 | 76 | 1.00 | Referent |
| 6.20-11.40 (vs ≤6.20) | 42 | 1.67 (1.12-2.49) | .01 |
| >11.40 (vs ≤6.20) | 49 | 1.06 (0.74-1.50) | .76 |
| Marginal treatment prescription dose, Gy | |||
| Continuous variable | 172 | 0.93 (0.87-1.00) | .04 |
| ≤17.5 | 124 | 1.00 | Referent |
| >17.5 (vs ≤17.5) | 48 | 0.65 (0.46-0.92) | .02 |
| Concurrent or adjuvant chemotherapyb | — | — |
aGK, Gamma Knife.
bCovariate failed to meet the a priori proportional hazard assumption for the model per Grambsch and Therneau,48 so results are not reported.