Table 2 Main meta-analysis results
Analysis | No. of studies | No. of patients | HR (95% CI) | p value | Model | Heterogeneity | Publication bias | ||
|---|---|---|---|---|---|---|---|---|---|
I 2 (%) | p | Begg’s p | Egger’s p | ||||||
Overall survival (OS) | 8 | 2615 | 1.90 (1.58–2.29) | < 0.001 | F | 0.0 | 0.48 | 0.06 | 0.03 |
Subgroup 1: treatment | Â | Â | Â | Â | Â | Â | Â | Â | Â |
  Surgery | 6 | 1922 | 2.27 (1.74–2.96) | < 0.001 | F | 0.0 | 0.68 | 0.26 | 0.27 |
  surgery + chemotherapy | 2 | 693 | 1.60 (1.24–2.07) | < 0.001 | F | 0.0 | 1.00 | - | - |
Subgroup 2: type of method used to obtain the HR | Â | Â | Â | Â | Â | Â | Â | Â | Â |
  Reported HR | 6 | 2167 | 1.89 (1.53–2.35) | < 0.001 | F | 23.3 | 0.26 | 0.13 | 0.06 |
  Calculated HR | 2 | 448 | 1.92 (1.34–2.74) | < 0.001 | F | 0.0 | 0.89 | - | - |
Subgroup 3: study regions | Â | Â | Â | Â | Â | Â | Â | Â | Â |
  Asia | 5 | 1213 | 2.08 (1.55–2.80) | < 0.001 | F | 0.0 | 0.83 | 0.09 | 0.07 |
  Europe | 2 | 951 | 2.18 (1.11–4.28) | 0.02 | R | 72.8 | 0.06 | - | - |
  Australia | 1 | 451 | 1.6 (1.10–2.20) | 0.008 | - | - | - | - | - |
Disease-free survival (DFS) | 3 | 950 | 2.16 (1.53–3.05) | < 0.001 | F | 0.0 | 0.667 | 1.000 | 0.825 |
Clinicopathological parameters | Â | Â | OR (95% CI) | Â | Â | Â | Â | Â | Â |
  Age (old vs. young) | 7 | 2040 | 1.24 (0.99–1.56) | 0.06 | F | 0.0 | 0.91 | 1.00 | 0.87 |
  Gender (female vs. man) | 7 | 2113 | 1.15 (0.93–1.43) | 0.21 | F | 23.2 | 0.25 | 1.00 | 0.81 |
  Tumor location (rectum vs. colon) | 6 | 1662 | 1.34 (1.06–1.69) | 0.01 | F | 0.0 | 0.97 | 0.71 | 0.57 |
  Differentiation (poorly vs. well and moderately) | 7 | 1340 | 1.04 (0.75–1.44) | 0.80 | F | 0.0 | 0.61 | 0.55 | 0.22 |
  Lymph node metastasis (yes vs. no) | 6 | 1671 | 2.62 (1.40–4.90) | 0.003 | R | 83.7 | 0.00 | 0.26 | 0.07 |
  Nodal status (N1 ~ 2 vs. N0) | 4 | 1230 | 2.68 (1.57–4.55) | < 0.001 | R | 59.9 | 0.06 | 0.09 | 0.02 |
  Distant metastasis (M1 vs. M0) | 3 | 768 | 3.22 (0.65–15.84) | 0.15 | R | 75.6 | 0.02 | 1.00 | 0.17 |
  TNM stage (III/IV vs. I/II) | 5 | 1732 | 3.03 (1.48–6.20) | 0.002 | R | 82.4 | 0.00 | 0.81 | 0.20 |
  Tumor depth (T 3/4 vs. T 1/2) | 6 | 1922 | 1.82 (1.35–2.46) | < 0.001 | F | 0.0 | 0.49 | 0.71 | 0.99 |
  Tumor size (size ≥ 5 cm vs. < 5 cm) | 6 | 1523 | 0.88 (0.67–1.16) | 0.37 | F | 0.0 | 0.48 | 1.00 | 0.99 |
  Vascular invasion (yes vs. no) | 2 | 977 | 1.29 (0.83–2.03) | 0.26 | F | 0.0 | 0.48 | - | - |
  Recurrence (yes vs. no) | 2 | 335 | 2.03 (0.87–4.73) | 0.100 | R | 68.2 | 0.076 | - | - |