TABLE 3.

Univariate Cox Proportional Hazards for Overall Survival From the Time of the Gamma Knife Procedure^a

		Hazard Ratio
Clinical Parameter	n	(95% Confidence Interval)	P
Male sex (vs female)	174	0.84 (0.61-1.15)	.27
Gliosarcoma (vs glioblastoma)	174	0.85 (0.45-1.62)	.62
Age at glioblastoma diagnosis	174	1.02 (1.01-1.03)	.005
Extent of first surgical resection (vs gross total resection)
Gross total	65	1.00	Referent
Near total	10	0.80 (0.38-1.81)	.64
Subtotal	69	0.99 (0.70-1.41)	.97
Biopsy	19	1.42 (0.84-2.39)	.19
Multiple pre-GK craniotomies	174	1.23 (0.89-1.70)	.21
Concurrent chemotherapy with initial fractionated radiotherapy	122
No chemotherapy with initial radiotherapy	51	1.00	Referent
Chemotherapy with initial radiotherapy	71	0.77 (0.59-1.01)	.06
Time from initial surgery to GK, mo
Continuous variable	174	0.99 (0.98-1.00)	.07
≤14.8	127	1.00	Referent
14.8-20.2 (vs ≤14.8)	20	1.66 (1.03-2.68)	.004
>20.2 (vs ≤14.8)	27	0.51 (0.32-0.79)	.003
Age at GK procedure, y
Continuous variable	174	1.02 (1.01-1.03)	.007
≤53.7	85	1.00	Referent
>53.7	89	1.54 (1.13-2.11)	.007
Multiple GK treatment targets (vs single lesion)	174	1.23 (0.89-1.70)	.21
Total treatment volume, cm3
Continuous variable	167	1.02 (1.00-1.04)	.11
≤5.10	64	1.00	Referent
5.10-5.77 (vs ≤5.10)	6	0.33 (0.12-0.92)	.03
>5.77 (vs ≤5.10)	97	1.24 (0.90-1.72)	.19
Marginal treatment prescription dose, Gy
Continuous variable	172	0.89 (0.82-0.96)	.002
≤15.5	56	1.00	Referent
>15.5 (vs ≤15.5)	116	0.57 (0.41-0.80)	.001
Concurrent or adjuvant chemotherapy	123
No chemotherapy after GK	46	1.00	Referent
Concurrent/adjuvant chemotherapy	77	0.85 (0.58-1.25)	.42

^aGK, Gamma Knife.