Table 3.

Multivariate Cox proportional hazard models for overall survival.

Variable	Overall survival (OS)
	HR (95% CI)	P value
T stage (T1+T2 vs. T3+T4)	1.689 (0.521–6.159)	0.235
N stage (N0 vs. N1+N2)	12.374 (1.506–48.180)	<0.001∗
AJCC stage (I+II vs. III+IV)	2.297 (0.689–5.982)	0.046∗
Differentiation (well vs. moderate+poor)	6.556 (2.254–10.842)	<0.001∗
IL-18 (high vs. low)	4.375 (1.279–8.220)	<0.001∗

HR: hazard ratio; CI: confidence interval; P values are based on likelihood ratio test; ^∗P < 0.05 indicates significant difference.