Table 2 Univariable and multivariable Cox proportional hazard regression analyses for mortality in trachea tumor patients

Race/ ethnicity

 Caucasians

1

 Others

0.926

Sex

 Male

1

1

reference

 Female

0.813

0.885

0.721–1.086

Marital status

 Non-married

1

1

reference

 Married

0.707

0.742

0.603–0.913

 Unknown

0.923

0.847

0.568–1.264

Age (year)

 < 65

1

1

reference

 ≥ 65

2.103

1.905

1.548–2.344

Surgery

 No

1

1

reference

 Yes

0.276

0.371

0.265–0.520

 Other/ unknown

0.881

1.076

0.707–1.638

Chemotherapy

 No

1

1

reference

 Yes

1.392

0.845

0.683–1.045

Radiotherapy

 No

1

 Yes

0.943

 Unknown

0.831

Histological types

 SCC

1

1

reference

 SGC

0.260

0.396

0.286–0.550

 Other/unknown

0.644

0.783

0.616–0.997

Extension

 E1

1

 E2

1.145

0.769

0.528–1.120

 E3

1.504

1.213

0.881–1.671

 E4

2.565

1.403

0.718–2.740

 Ex

1.456

1.546

1.064–2.247

 N classification

 N0

1

1

reference

 N1

2.330

1.426

1.046–1.944

 Nx

1.376

2.185

1.364–3.502

M classification

 M0

1

1

reference

 M1

2.648

1.238

0.492–3.112

 M2

3.129

2.055

1.424–2.967

 Mx

1.087

0.342

0.205–0.568

Grade

 I-II

1

1

reference

 III-IV

1.526

1.337

1.029–1.737

 Unknown/other

1.005

1.068

0.837–1.363

Tumor size

 < 3.1 cm

1

1

reference

 3.1-5.0 cm

1.467

0.979

0.679–1.412

 > 5.0 cm

2.087

1.570

0.903–2.731

 Unknown

1.704

1.258

0.925–1.711