Table 2 Univariate and Multivariate analyses of the 5-year OS in N0 patients

Age

p < 0.001

p < 0.001

 age < 55

Ref

/

Ref

/

 55 ≤ age < 65

1.06

0.62–1.79

1.04

0.62–1.80

 age ≥ 65

2.48

1.59–3.86

2.16

1.39–3.38

Sex

p = 0.06

 female

Ref

/

 male

0.63

0.39–1.02

Tumor location

p < 0.001

 upper third

Ref

/

 middle third

2.47

1.66–3.67

 lower third

1.58

0.94–2.66

Tumor differentiation

p = 0.43

 well differentiated

Ref

/

 moderately differentiated

0.84

0.54–1.29

 poorly differentiated or undifferentiated

0.92

0.58–1.45

Lymphovascular Invasion

p < 0.001

p < 0.001

 no

Ref

/

Ref

/

 yes

3.26

2.21–4.83

2.47

1.64–3.72

T-stage

p < 0.001

p < 0.001

 T1

Ref

/

Ref

/

 T2

1.73

0.93–3.22

1.54

0.83–2.88

 T3

3.6

2.07–6.26

2.62

1.48–4.64

 T4

3.8

2.23–6.73

3.18

1.82–5.59