Table 2 Univariate and multivariate analysis of Overall Survival (OS) in PDAC patients (n = 161)

Age

< 60 (ref)

≥ 60

1.030

0.745-1.425

0.857

Gender

Male (ref)

Female

0.885

0.640-1.225

0.459

Differentiation

Well (ref)

Moderate

1.877

1.084-3.251

0.059

1.996

0.951-4.191

0.068

Poor

2.446

1.434-4.174

0.007^**

2.331

1.075-5.055

0.032^*

TNM stage

I (ref)

II

1.178

0.786-1.765

0.439

0.826

0.524-1.304

0.413

III

1.926

1.069-3.470

0.011^*

1.116

0.607-2.052

0.723

Lymph node metastasis ^a

Negative (ref)

Positive

1.731

1.251-2.395

<0.001^***

Perineural invasion

Negative (ref)

Positive

1.554

0.999-2.418

0.087

Long-term smoking ^b

No (ref)

Yes

1.744

0.970-3.136

0.018^*

2.102

1.271-3.476

0.004^**

High-fat diet

No (ref)

Yes

1.343

0.818-2.203

0.191

Chronic pancreatitis

No (ref)

Yes

1.459

0.892-2.387

0.081

circCUL2 expression

Low (ref)

High

2.222

1.575-3.133

<0.001^***

2.374

1.645-3.426

<0.001^***

Abbreviations: HR = hazard ratio; 95% CI = 95% confidence interval; TNM = tumor node metastasis; ref = reference. ^a As lymph node metastasis is included in the TNM stage, we didn’t include it in the multivariate analysis. ^b Long-term smoking (duration ≥ 29 years). Cox regression analysis, * p < 0.05, ** p < 0.01, *** p<0.001.