Table 3.

Cox Proportional Hazards Model for Overall Survival

Covariate	HR	95% CI	P
Time from surgery to start of RT, weeks
≤ 2	RL		—
> 2-3	0.97	0.87 to 1.07	.49
> 3-4	0.91	0.82 to 1.01	.07
> 4	0.84	0.75 to 0.95	.004
RPA
III	RL		—
IV	1.72	1.53 to 1.93	< .0001
V	2.74	2.42 to 3.10	< .0001
VI	4.39	3.74 to 5.14	< .0001

Abbreviations: HR, hazard ratio; RT, radiation therapy; RL, reference level; RPA, recursive partitioning analysis.