Outcome | Studies | Participants | RR & 95%CI | P value | I2 | Egger's test P value | Class of Evidence |
---|---|---|---|---|---|---|---|
1. Patient characteristic | |||||||
 1.1 Age | 6 | 1584 | 1.06 [0.90, 1.25] | 0.47 | 36% | - | Class II |
 1.2 Male | 17 | 4146 | 0.94 [0.86, 1.03] | 0.16 | 24% | 0.185 | Class I |
 1.3 Elevated CEA | 9 | 2417 | 1.56 [1.19, 2.04] | 0.001 | 81% | - | Class II |
 1.4 Elevated CA199 | 4 | 1138 | 1.48 [1.20, 1.81] |  < 0.001 | 36% | - | Class II |
2. Primary tumor characteristics | |||||||
 2.1 Poor differentiation | 6 | 1362 | 1.13 [1.03, 1.25] | 0.01 | 0% | - | Class I |
 2.2 Lymph node metastasis | 19 | 4471 | 1.31 [1.17, 1.48] |  < 0.001 | 47% | 0.035 | Class II |
 2.3 T3-4 | 10 | 2558 | 1.04 [0.93, 1.17] | 0.48 | 0% | 0.623 | Class I |
 2.4 Rectal tumor | 17 | 3959 | 1.00 [0.91, 1.11] | 0.93 | 41% | 0.897 | Class I |
3. Liver metastases characteristics | |||||||
 3.1 Synchronous metastases | 16 | 3702 | 1.23 [0.89, 1.71] | 0.21 | 90% | 0.121 | Class III |
 3.2 More metastases | 13 | 3254 | 1.46 [1.26, 1.68] |  < 0.001 | 57% | 0.206 | Class II |
 3.3 Larger metastases | 7 | 1862 | 1.18 [1.04, 1.34] | 0.01 | 29% | - | Class I |
 3.4 Bilobar distribution | 13 | 2717 | 1.37 [1.21, 1.55] |  < 0.001 | 40% | 0.811 | Class I |
 3.5 Extrahepatic metastases | 4 | 1332 | 1.13 [0.99, 1.29] | 0.06 | 25% | - | Class I |
4. Surgical procedures and operative outcome | |||||||
 4.1 Laparoscopic resection | 3 | 855 | 0.87 [0.72, 1.05] | 0.16 | 0% | - | Class II |
 4.2 Simultaneous resection | 8 | 2161 | 1.00 [0.83, 1.21] | 0.98 | 55% | - | Class II |
 4.3 Major hepatectomy | 12 | 2588 | 1.16 [1.07, 1.25] |  < 0.001 | 0% | 0.329 | Class I |
 4.4 Positive surgical margin | 12 | 3187 | 1.33 [1.20, 1.48] |  < 0.001 | 34% | 0.505 | Class I |
 4.5 Preoperative chemotherapy | 12 | 2606 | 1.12 [0.97, 1.28] | 0.12 | 58% | 0.074 | Class III |
 4.6 Postoperative chemotherapy | 12 | 3200 | 0.93 [0.78, 1.11] | 0.40 | 74% | 0.616 | Class II |
 4.7 Blood transfusion | 9 | 2319 | 1.10 [0.96, 1.25] | 0.16 | 39% | - | Class I |
 4.8 Postoperative complications | 6 | 1731 | 1.28 [1.13, 1.44] |  < 0.001 | 30% | - | Class I |