Table 2 Subgroup analyses for OS, PFS, and RFS

OS

Publication year

Before 2010

1.85 (1.43–2.40)

< 0.001

22.3

0.266

0.039

2010 or after

1.29 (0.94–1.77)

0.111

67.6

0.001

Country

Eastern

1.15 (0.77–1.72)

0.485

74.2

<0.001

0.013

Western

1.78 (1.47–2.15)

<0.001

4.2

0.400

Sample size

≥ 100

1.56 (1.28–1.89)

<0.001

44.6

0.036

0.029

< 100

1.64 (0.31–8.64)

0.562

85.0

0.001

Mean age (years)

≥ 50.0

1.16 (0.63–2.13)

0.638

83.7

<0.001

0.055

< 50.0

1.67 (1.34–2.08)

<0.001

17.1

0.295

Not reported

1.68 (1.26–2.24)

<0.001

0.0

0.425

Treatment strategy

Surgery alone

1.64 (1.05–2.57)

0.031

66.0

0.012

0.774

Other

1.41 (1.06–1.89)

0.020

65.9

0.002

Cutoff value

≥ 300

1.53 (1.14–2.05)

0.004

67.7

<0.001

0.851

< 300

1.43 (0.97–2.11)

0.069

46.4

0.113

Adjusted

Yes

1.68 (1.38–2.05)

<0.001

0.0

0.748

0.149

No

1.39 (0.98–1.96)

0.063

70.7

<0.001

Study quality

High

1.67 (1.37–2.03)

<0.001

0.0

0.917

0.174

Low

1.44 (1.00–2.07)

0.052

71.6

<0.001

PFS

Publication year

Before 2010

1.54 (0.80–2.96)

0.196

–

–

0.699

2010 or after

1.29 (1.02–1.64)

0.036

32.4

0.170

Country

Eastern

1.18 (0.90–1.55)

0.241

33.7

0.183

0.115

Western

1.71 (1.22–2.39)

0.002

0.0

0.790

Sample size

≥ 100

1.39 (1.16–1.67)

<0.001

0.0

0.442

0.235

< 100

1.08 (0.22–5.24)

0.919

69.2

0.071

Mean age (years)

≥ 50.0

1.18 (0.72–1.94)

0.508

63.8

0.063

0.215

< 50.0

0.66 (0.27–1.62)

0.365

–

–

Not reported

1.48 (1.16–1.89)

0.001

0.0

0.756

Treatment strategy

Surgery alone

1.31 (0.93–1.84)

0.127

0.0

0.797

0.794

Other

1.28 (0.92–1.78)

0.144

49.9

0.076

Cutoff value

≥ 300

1.42 (1.12–1.80)

0.004

19.8

0.284

0.228

< 300

1.02 (0.63–1.65)

0.936

23.6

0.253

Not reported

2.72 (0.61–12.10)

0.189

–

–

Adjusted

Yes

1.45 (1.11–1.88)

0.006

0.0

0.547

0.539

No

1.23 (0.86–1.75)

0.266

43.9

0.113

Study quality

High

1.52 (1.24–1.88)

<0.001

0.0

0.789

0.046

Low

0.96 (0.57–1.60)

0.867

37.8

0.185

RFS

Publication year

Before 2010

8.50 (0.78–92.40)

0.079

–

–

0.173

2010 or after

1.60 (1.22–2.10)

0.001

0.7

0.388

Country

Eastern

1.71 (1.24–2.34)

0.001

0.0

0.587

0.624

Western

1.98 (0.75–5.24)

0.167

53.9

0.114

Sample size

≥ 100

1.55 (1.17–2.04)

0.002

0.0

0.369

0.140

< 100

3.35 (1.25–9.00)

0.017

0.0

0.400

Mean age (years)

< 50.0

1.51 (1.04–2.18)

0.029

17.7

0.297

0.308

Not reported

2.52 (0.82–7.71)

0.105

29.0

0.235

Treatment strategy

Surgery alone

1.75 (1.28–2.40)

<0.001

0.3

0.367

0.399

Other

1.54 (0.64–3.73)

0.334

53.7

0.141

Cutoff value

≥ 300

2.52 (0.82–7.71)

0.105

29.0

0.235

0.308

< 300

1.51 (1.04–2.18)

0.029

17.7

0.297

Adjusted

Yes

2.40 (0.59–9.69)

0.221

45.3

0.176

0.872

No

1.63 (1.00–2.66)

0.048

33.8

0.221

Study quality

High

1.60 (1.09–2.36)

0.017

–

–

0.886

Low

1.78 (1.04–3.05)

0.034

38.2

0.183