Table 4 Univariate and multivariate cox regression analysis before and after IPTW adjustment in post-PSM SEER cohort

Age

  < 55

Reference

Reference

  > =55

1.69 (1.15–2.48)

0.007

1.53 (0.95–2.45)

0.079

Sex

 Female

Reference

Reference

Reference

 Male

1.06 (0.73–1.54)

0.778

1.28 (0.75–2.18)

0.373

1.53 (0.92–2.54)

0.100

PTS

 Stamoch

Reference

Reference

Reference

Reference

 Small intestine

0.21 (0.11–0.38)

< 0.001

0.51 (0.25–0.14)

0.064

0.26 (0.13–0.51)

< 0.001

0.49 (0.22–1.09)

0.079

 Colorectum

0.98 (0.64–1.5)

0.931

1.16 (0.75–1.77)

0.507

0.85 (0.44–1.63)

0.614

0.90 (0.48–1.69)

0.747

Grade

 Well differentiation G1

Reference

Reference

Reference

Reference

 Moderate differentiation G2

0.98 (0.55–1.76)

0.951

1.59 (0.86–2.93)

0.141

1.46 (0.85–2.49)

0.167

1.60 (0.92–2.79)

0.098

 Poor differentiation G3

5.78 (3.24–10.31)

< 0.001

4.11 (2.23–7.58)

< 0.001

2.87 (1.15–7.94)

0.024

2.86 (1.27–6.45)

0.011

 NEC

5.40 (2.9–10.05)

< 0.001

2.81 (1.46–5.41)

0.002

6.68 (3.28–13.59)

< 0.001

4.12 (1.88–9.06)

< 0.001

T

 T1

Reference

Reference

Reference

 T2

1.48 (0.8–2.74)

0.214

1.60 (0.83–3.11)

0.162

0.49 (0.12–2.08)

0.337

 T3

1.18 (0.61–2.23)

0.623

1.30 (0.21–3.31)

0.583

0.52 (0.13–2.08)

0.356

 T4

1.76 (0.91–3.5)

0.090

2.89 (1.38–6.05)

0.005

0.73 (0.17–3.19)

0.679

PTR

 No

Reference

Reference

Reference

Reference

 Yes

0.24 (0.16–0.37)

< 0.001

0.40 (0.24–0.66)

< 0.001

0.41 (0.23–0.71)

< 0.001

0.39 (0.21–0.74)

0.004

Primary tumor size

  < 2

Reference

Reference

Reference

Reference

  > =2

4.02 (2.29–7.07)

< 0.001

1.78 (0.96–3.29)

0.066

2.79 (1.46–5.33)

0.002

2.07 (0.53–8.18)

0.297

Extrahepatic metastases

 No

Reference

Reference

Reference

 Yes

2.30 (1.54–3.43)

< 0.001

2.44 (1.49–3.98)

< 0.001

1.68 (0.93–3.01)

0.083