Table 6. Multivariate Cox regression prognostic analysis of OS.

Factors	Hazard ratio	95% confidence interval	p value
Maximal tumor size
≤2cm	Ref.
2-4cm	0.445	0.260-0.760	0.003
>4cm	0.446	0.253-0.787	0.005
LN metastasis
Negative	Ref.
Positive	0.096	0.057-0.160	<0.001
Distant metastasis
Negative	Ref.
Positive	0.309	0.146-0.651	0.002
Groups
B-T	Ref.
B only	2.261	1.378-3.710	0.001

Abbreviations: LN, lymph nodes