Table 2. Univariate and multivariate Cox regression analysis.

Variable	Cases	Univariate Cox regression analysis				Multivariate Cox regression analysis
		Hazard ratio (95% CI)	χ2	P		Hazard ratio (95% CI)	χ2	P
Gender
Male	1,448	1	2.451	0.117
Female	383	0.891 (0.772–1.029)
Age (years)
≤72	1,411	1	28.486	0.000		1	35.318	0.000
>72	420	1.416 (1.246–1.609)				1.482 (1.301–1.687)
Primary site
Cervical esophagus	34	1	23.720	0.001		1	12.117	0.059
Upper third of esophagus	110	0.851 (0.543–1.333)				0.946 (0.599–1.494)
Middle third of esophagus	311	0.922 (0.614–1.384)				0.991 (0.652–1.507)
Lower third of esophagus	1,227	0.728 (0.492–1.076)				0.845 (0.556–1.284)
Abdominal esophagus	14	1.244 (0.628–2.466)				1.524 (0.755–3.076)
Overlapping lesion of esophagus	75	1.174 (0.739–1.865)				1.197 (0.738–1.941)
Thoracic esophagus	60	0.807 (0.493–1.323)				0.826 (0.498–1.369)
Grade
I	95	1	8.120	0.044		1	8.351	0.039
II	806	0.921 (0.706–1.201)				0.902 (0.691–1.178)
III	899	1.081 (0.831–1.406)				1.071 (0.821–1.397)
IV	31	1.247 (0.766–2.031)				1.231 (0.750–2.020)
Pathological type
Squamous cell carcinoma	613	1	8.877	0.012		1	2.857	0.240
Adenocarcinoma	1037	0.832 (0.737–0.940)				0.893 (0.764–1.043)
Others	181	0.857 (0.698–1.052)				0.840 (0.668–1.057)
T stage
T1	233	1	22.260	0.000		1	11.926	0.008
T2	286	0.811 (0.650–1.012)				0.859 (0.686–1.076)
T3	1,144	1.049 (0.880–1.250)				1.008 (0.839–1.210)
T4	168	1.412 (1.114–1.788)				1.311 (1.024–1.677)
N stage
N0	556	1	37.300	0.000		1	34.297	0.000
N1	900	1.189 (1.040–1.361)				1.193 (1.039–1.369)
N2	308	1.455 (1.229–1.722)				1.465 (1.229–1.745)
N3	67	2.128 (1.599–2.833)				2.109 (1.574–2.827)
Tumor size (mm)
≤63	1,325	1	31.857	0.000		1	17.842	0.000
>63	506	1.422 (1.259–1.608)				1.317 (1.159–1.497)
Race
White	1,543	1	7.125	0.068
Black	138	1.248 (1.020–1.526)
Asian	132	1.195 (0.962–1.485)
Others	18	0.815 (0.406–1.634)