Table 2 Cox regression analyses for cancer-specific mortality of patients

Sex

Male

1

reference

1

reference

Female

0.757

0.582─0.985

0.911

0.692─1.200

Age (year)

≤ 65

1

reference

1

reference

> 65

1.275

0.981─1.657

1.232

0.940─1.615

Race

White

1

reference

Other/ unknown

1.301

0.956─1.770

Marital status

Unmarried

1

reference

Married

0.978

0.750─1.276

Unknown

0.842

0.410─1.727

Location

Upper

1

reference

1

reference

Lower

1.169

0.860─1.589

1.318

0.963─1.804

Other/ unknown

2.049

1.338─3.136

1.491

0.954─2.331

Laterality

Left

1

reference

Right

1.114

0.856─1.450

Other/ unknown

5.907

0.816─42.75

T stage

T1

1

reference

1

reference

T2

1.464

1.058─2.026

1.506

1.080─2.101

T3

1.991

1.289─3.075

1.997

1.269─3.142

T4

2.812

1.969─4.016

2.135

1.428─3.194

 N stage

N0

1

reference

1

reference

N1

2.304

1.592─3.334

2.846

1.935─4.186

N2

2.908

2.168─3.900

2.488

1.742─3.553

Grade

I─II

1

reference

III

1.085

0.443─2.656

IV

0.780

0.300─2.026

Unknown

1.441

0.583─3.560

Surgery

No

1

reference

1

reference

Yes

0.306

0.235─0.399

0.315

0.218─0.457

Radiotherapy

No

1

reference

1

reference

Yes

1.947

1.492─2.541

0.847

0.587─1.223

Unknown

1.521

0.561─4.121

0.668

0.237─1.881

Chemotherapy

No

1

reference

1

reference

Yes

0.306

0.235─0.399

0.532

0.384─0.739