Table 3 Summary of univariate and multivariate Cox regression analysis of overall survival duration

Age

≥65vs. <65 years

0.573

1.160

0.692-1.946

Gender

Male vs. female

0.061

0.574

0.322-1.025

Smoking

Yes vs. No

0.05

0.586

0.344-0.999

0.145

0.656

0.372-1.156

Pathology classification

Squamous vs. Adenocarcinoma vs. Small cell undifferentiated

0.883

1.036

0.648-1.656

Differentiation degree

High vs. Middle vs.Low

0.004

1.660

1.176-2.343

0.001

2.076

1.370-3.144

T classification

T₁-T₂ vs. T₃-T₄

0.018

2.020

1.130-3.612

0.609

0.819

0.381-1.759

N classification

N₀-N1 vs. N_2--N₃

0.003

2.259

1.323-3.860

0.996

1.003

0.273-3.692

M classification

M₀ vs. M₁

0.039

3.436

1.066-11.078

0.088

3.666

0.825-16.293

Clinical stage

I-II vs. III-IV

0.000

2.586

1.515-4.412

0.470

1.605

0.445-5.787

CDK4 expression

High vs. Low *

0.000

6.420

3.473-11.867

0.000

6.714

3.329-13.451