Table 3 Univariable and multivariable Cox proportional hazard regression analyses of the characteristics in training cohort

Sex

 Male

1 (reference)

 Female

1.170

0.665–2.061

0.586

Age (year, continuous)

1.024

0.995–1.053

0.107

Smoking status

 No

1 (reference)

 Yes

1.305

0.764–2.231

0.330

Drinking status

 No

1 (reference)

 Yes

1.627

0.949–2.790

0.077

Differentiation

 Well-moderate

1 (reference)

 Poor

0.681

0.406–1.140

0.144

pT stage

 T2

1 (reference)

 T3

1.677

0.952–2.954

0.073

pTNM stage

 IB

1 (reference)

 IIA

2.080

1.101–3.930

0.024

1.050–3.761

Tumor length (cm, continuous)

1.031

0.889–1.197

0.684

Surgery approach

 Left

1 (reference)

 Right

0.624

0.330–1.179

0.146

NLNs (continuous)

0.960

0.935–0.985

0.002

0.938–0.989

PD-L1 expression

 Low

1 (reference)

 High

4.910

2.770–8.702

< 0.001

2.669–8.438

Dissection of left gastric artery LNs

 No

1 (reference)

 Yes

4.338

0.599–31.44

0.146

Dissection of subcarinal LNs

 No

1 (reference)

 Yes

0.965

0.349–2.668

0.946

LNs dissection of left recurrent laryngeal nerve

 No

1 (reference)

 Yes

1.362

0.756–2.452

0.304

LNs dissection of right recurrent laryngeal nerve

 No

1 (reference)

 Yes

1.128

0.634–2.008

0.681