Table 1 Subgroup analyses

Mortality

Studies with a score of ≥6 points [6, 7, 9, 24, 52, 55, 56, 58]

8

1.43 (1.26 to 1.63); P <0.001

I² = 12.4%; P = 0.33

Studies with a score of 5 points [50, 51]

2

2.20 (0.77 to 6.34); P = 0.14

I² = 52.6%; P = 0.15

Studies with a score of <5 points [19–21, 53, 54, 57, 59, 60]

8

1.48 (1.05 to 2.08); P = 0.03

I² = 55.5%; P = 0.03

Time-to-disease progression

Study with a score of ≥6 points [52]

1

1.52 (1.04 to 2.23); P <0.05

Studies with a score of 5 points [50, 51]

2

1.91 (0.64 to 5.70); P = 0.25

I² = 77.4%; P = 0.04

Studies with a score of <5 points [19, 21, 53]

3

1.90 (0.81 to 4.46); P = 0.14

I² = 54.9%; P = 0.11

Lymph node metatasis

Study with a score of ≥6 points [6, 7, 9, 55, 56, 58]

6

1.21 (0.97 to 1.51); P = 0.09

I² = 68.5%; P = 0.007

Studies with a score of <5 points [8, 11, 54, 57, 60–66]

11

1.47 (1.25 to 1.73); P <0.001

I² = 38.5%; P = 0.09

Distant metastasis

Studies with a score of ≥6 points [9, 52, 55, 58]

4

1.81 (1.28 to 2.57); P = 0.001

I² = 0.0%; P = 0.99

Studies with a score of <5 points [8, 11, 54, 57, 61]

5

1.68 (1.08 to 2.62); P = 0.02

I² = 0.0%; P = 0.74

B. Adjusted versus unadjusted results for Mortality

Studies with results from multivariable analysis [6, 7, 9, 24, 51, 52, 54–56, 58]

10

1.44 (1.28 to 1.62); P <0.001

I^{2 =} 21.7%; P = 0.24

Studies without results from multivariable analysis [19–21, 50, 53, 57, 59, 60]

8

1.48 (0.97 to 2.26); P = 0.07

I^{2 =} 55.3%; P = 0.03