Table 4 Cox regression models for predicting overall survival

G1 (reference)

1

1

1

G2

1.551

1.193–2.018

0.001

1.548

1.190–2.013

0.001

1.563

1.202–2.034

<0.001

G3

1.191

0.950–1.495

0.130

1.182

0.942–1.484

0.148

1.178

0.939–1.478

0.157

Upper tumor (reference)

1

1

1

Middle tumor

1.192

0.684–2.075

0.535

1.174

0.674–2.044

0.571

1.188

0.682–2.068

0.543

Lower tumor

1.180

0.677–2.056

0.560

1.148

0.658–2.001

0.627

1.156

0.664–2.015

0.608

T1 (reference)

1

1

1

T2

1.757

1.220–2.531

0.002

1.685

1.167–2.433

0.043

1.636

1.033–2.362

0.008

T3

2.296

1.651–3.193

<0.001

2.133

1.522–2.990

<0.001

2.067

1.478–2.892

<0.001

T4

3.066

2.070–4.544

<0.001

2.869

1.924–4.270

<0.001

2.772

1.864–4.123

<0.001

N0 (reference)

1

1

1

N1

1.717

1.418–2.079

<0.001

1.725

1.425–2.089

<0.001

1.700

1.404–2.057

<0.001

N2

2.822

2.304–3.457

<0.001

2.791

2.278–3.418

<0.001

2.777

2.268–3.402

<0.001

N3

4.705

3.670–6.032

<0.001

4.654

3.629–5.968

<0.001

4.618

3.601–5.923

<0.001

Tumor length

1.170

1.005–1.363

0.043

1.058

1.020–1.097

0.002

Bootstrap-corrected C-index (%)

69.4

69.6

69.8