Table 1. The characteristics of the included studies.
| Author | Year | Region | Number of patients | Age (years) | Gender (Male/Female) | Tumor location (Colon/Rectum) | TNM stage | Dukes stage | Treatment | Cut-off value | Follow-up (months) | Survival analysis | HR | LL | UL | NOS score |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Suee Lee | 2017 | South Korea | 170 | 28-84(63b) | 107/63 | 110/60 | I-IV | NA | Surgery | 1.4mg/L | >60 | survival curve | 5.890 | 2.050 | 16.950 | 7 |
| Hong Tingting | 2017 | China | 505 | 27-93(62.97a) | 265/240 | NA | I-IIIC | NA | Surgery | 0.216mg/L | 43* | multivariate | 1.720 | 0.700 | 4.230 | 8 |
| Kemal TekeGin | 2016 | Turkey | 134 | 31-84(62.5b) | 84/50 | 94/40 | I-IV | NA | Surgery or RFA | 0.96mg/L | 18* | multivariate | 1.873 | 1.032 | 3.494 | 8 |
| Zhao Shuangshuang | 2016 | China | 62 | 35-84 | 41/21 | 38/24 | NA | NA | Chemotherapy | 0.8mg/L | 50 | multivariate | 2.38 | 1.082 | 5.235 | 8 |
| Xu Haifei | 2015 | China | 60 | 37-86(61.3a) | 32/28 | 26/34 | NA | A-D | Surgery | 0.3mg/L | 52.5* | multivariate | 2.557 | 1.003 | 6.516 | 8 |
| Ehsan Motavaf | 2014 | Denmark | 166 | 38-94 (69b) | 103/63 | 87/79 | NA | NA | Surgery | 0.3mg/L | 60* | multivariate | 2.200 | 1.100 | 4.800 | 8 |
| Zhu Liming | 2014 | China | 74 | 31-74(55.5b) | 40/34 | 44/30 | NA | NA | Chemotherapy | 1.9mg/L | 18.4* | multivariate | 3.520 | 1.280 | 9.670 | 8 |
| Xue Liying | 2014 | China | 40 | >=70(n=22); <70(n=18) | 26/14 | 21/19 | NA | NA | Chemotherapy | 5.0mg/L | 36 | multivariate | 4.386 | 2.101 | 9.174 | 8 |
| Wang Junfeng | 2013 | China | 341 | 23-90 | 178/163 | 188/153 | I-III | NA | Surgery | 0.5mg/L | 64* | multivariate | 1.829 | 0.110 | 7.893 | 8 |
| Manabu Yamamoto | 2012 | Japan | 42 | >=70(n=30); <70(n=12) | 26/16 | 25/17 | NA | NA | Chemotherapy | 1.0mg/L | 14.1* | multivariate | 3.749 | 1.127 | 18.160 | 8 |
| Gurkan Tellioglu | 2012 | America | 242 | 63a | 81/161 | NA | NA | NA | RFA | 1.0mg/L | 22* | multivariate | 2.090 | 1.840 | 2.360 | 8 |
| Corrado Pedrazzani | 2010 | Italy | 199 | 26-94(67.7b) | 118/81 | 141/58 | NA | NA | Surgery | 0.25mg/L | 60 | survival curve | 1.500 | 0.860 | 2.610 | 8 |
| Kilic M | 2007 | Turkey | 51 | 29-80(60.9a) | 34/17 | NR | NA | A-D | Surgery | 0.375mg/L | 20* | survival curve | 2.970 | 1.180 | 7.480 | 6 |
| Kimberly Blackwell | 2004 | America | 104 | 23-85(61b) | 43/57 | NA | NA | NA | Chemotherapy | 0.001332mg/L | >25 | multivariate | 1.180 | 1.020 | 1.371 | 8 |
| Masatoshi Oya | 2001 | Japan | 93 | 27-84(62.7a) | 62/31 | 51/42 | I-III | NA | Surgery | 0.85mg/L | 54.7* | multivariate | 1.874 | 1.001 | 3.497 | 7 |
a: mean age; b: median age; NA: not available; RFA: radio frequency ablation; *: median of follow-up; NOS: Newcastle-Ottawa Scale