Table 2.

Univariate analysis, multivariate analysis and cox regression analysis for building the model

Variable	Univariate analysis P	Multivariate anlaysis			Selected factors for building model
		Hazard ratio	95% CI	P	Hazard ratio	95% CI	P
Age, years	< 0.001			< 0.001			< 0.001
≥ 70		Reference			Reference
< 70		1.733	1.536–1.956	< 0.001	1.745	1.547–1.968	< 0.001
Tumor histology	< 0.001			< 0.001			< 0.001
Papillary histology		Reference			Reference
Adenocarcinoma and others histology		1.667	1.236–2.248	< 0.001	1.684	1.251–2.266	< 0.001
Squamous histology		2.111	1.410–3.161	< 0.001	2.282	1.536–3.390	< 0.001
Tumor grade	< 0.001			0.469
I		Reference
II		0.997	0.814–1.221	0.975
III		1.103	0.895–1.360	0.358
IV		1.103	0.759–1.603	0.607
Tumor size, cm	< 0.001			0.156
< 3		Reference
3–5		1.116	0.968–1.287	0.131
5–10		1.133	0.965–1.331	0.127
≥ 10		1.343	0.989–1.825	0.059
Pathologic T category	< 0.001			< 0.001			< 0.001
T1		Reference			Reference
T2		0.994	0.783–1.263	0.963	1.003	0.790–1.273	0.982
T3		1.960	1.530–2.510	< 0.001	2.064	1.619–2.632	< 0.001
T4		2.244	1.570–3.206	< 0.001	2.384	1.682–3.381	< 0.001
Pathologic N category	< 0.001			< 0.001			< 0.001
N0		Reference			Reference
N1		2.024	1.770–2.316	< 0.001	2.076	1.818–2.370
N2		2.026	1.557–2.637	< 0.001	2.086	1.606–2.709
Pathologic M category	< 0.001			< 0.001			< 0.001
M0		Reference			Reference
M1		2.242	1.915–2.626	< 0.001	2.300	1.969–2.687	< 0.001
Sex	0.083
Male
Female
Resection type	0.062
Radical resection
Palliative resection
Tumor number	< 0.001*
Single tumor
Multiple tumors

^*The tumor number was excluded in the multivariable analysis, since its hazard ratio was less than 1, which was contrary to the factor that patients with more tumors had worse survival outcome