Table 5 Univariate and multivariate analyses of OS

Age (years)

≤ 60

>  60

1.186

1.128–1.248

< 0.001

1.203

1.143–1.267

< 0.001

1.228

1.101–1.371

< 0.001

1.150

1.030–1.284

0.013

Gender

Female

NI

NI

Male

1.046

0.999–1.096

0.053

1.011

0.948–1.077

0.746

Race

Black

White

0.905

0.845–0.970

0.005

0.934

0.872–1.002

0.056

0.898

0.814–0.991

0.032

0.931

0.843–1.028

0.156

Others

0.890

0.804–0.986

0.026

0.920

0.830–1.020

0.113

0.875

0.755–1.013

0.074

0.948

0.818–1.099

0.477

Tumor site

Head

Body

1.363

1.273–1.461

< 0.001

0.929

0.865–0.998

0.043

1.307

1.188–1.437

< 0.001

0.966

0.874–1.066

0.489

Tail

1.412

1.317–1.513

< 0.001

0.988

0.919–1.062

0.751

1.456

1.326–1.599

< 0.001

1.039

0.942–1.146

0.443

Pancreatic duct

1.458

1.336–1.590

< 0.001

0.995

0.910–1.089

0.921

1.483

1.314–1.674

< 0.001

1.019

0.899–1.156

0.769

Others

1.424

1.304–1.555

< 0.001

0.971

0.886–1.064

0.522

1.459

1.299–1.638

< 0.001

0.931

0.824–1.053

0.254

Tumor size (cm)

≤ 2

2~4

1.429

1.310–1.559

< 0.001

1.159

1.034–1.300

0.011

1.392

1.238–1.564

< 0.001

1.215

1.033–1.430

0.019

> 4

2.162

1.980–2.361

< 0.001

1.407

1.252–1.581

< 0.001

2.127

1.888–2.397

< 0.001

1.459

1.236–1.722

< 0.001

Tumor grade

Well

Moderate

1.116

1.028–1.212

0.009

1.233

1.135–1.339

< 0.001

1.030

0.923–1.148

0.599

1.204

1.078–1.345

0.001

Poor

1.601

1.476–1.736

< 0.001

1.584

1.459–1.719

< 0.001

1.412

1.267–1.573

< 0.001

1.446

1.295–1.615

< 0.001

Undifferentiated

1.697

1.416–2.034

< 0.001

1.357

1.131–1.628

0.001

1.633

1.320–2.019

< 0.001

1.377

1.111–1.707

0.004

T stage

T0

T1

0.200

0.139–0.287

< 0.001

0.334

0.231–0.483

< 0.001

0.250

0.164–0.380

< 0.001

0.374

0.242–0.577

< 0.001

T2

0.471

0.335–0.661

< 0.001

0.451

0.313–0.650

< 0.001

0.547

0.370–0.807

0.002

0.480

0.311–0.742

0.001

T3

0.288

0.205–0.404

< 0.001

0.444

0.309–0.638

< 0.001

0.351

0.238–0.517

< 0.001

0.483

0.313–0.743

0.001

T4

0.480

0.342–0.674

< 0.001

0.450

0.313–0.648

< 0.001

0.578

0.391–0.855

0.006

0.462

0.299–0.714

< 0.001

N stage

N0

N1

0.925

0.881–0.971

0.002

1.100

1.046–1.156

< 0.001

0.905

0.845–0.969

0.004

1.096

1.021–1.176

0.011

N2

0.591

0.544–0.641

< 0.001

1.396

1.268–1.537

< 0.001

0.575

0.511–0.647

< 0.001

1.408

1.226–1.616

< 0.001

Metastasis

Absent

Present

2.874

2.739–3.015

< 0.001

1.702

1.608–1.802

< 0.001

2.911

2.723–3.112

< 0.001

1.719

1.589–1.859

< 0.001

Surgery

Performed

Recommended, not performed

3.367

2.948–3.846

< 0.001

2.570

2.232–2.959

< 0.001

3.365

2.881–3.929

< 0.001

2.626

2.221–3.105

< 0.001

Not recommended

3.431

3.255–3.618

< 0.001

2.608

2.419–2.813

< 0.001

3.582

3.323–3.861

< 0.001

2.684

2.416–2.982

< 0.001

Radiotherapy

No

Yes

0.369

0.341–0.399

< 0.001

0.887

0.813–0.969

0.008

0.369

0.330–0.412

< 0.001

0.860

0.759–0.974

0.017

Chemotherapy

No

Yes

0.445

0.425–0.467

< 0.001

0.435

0.414–0.457

< 0.001

0.450

0.422–0.480

< 0.001

0.451

0.422–0.483

< 0.001

Prior cancer

Without

With

1.030

0.925–1.147

0.587

1.014

0.910–1.130

0.796

0.993

0.889–1.108

0.894

1.018

0.912–1.136

0.754