Table 1.
Characteristics of studies included in the meta-analysis
| Author | Region | Cancer Type | Sample size | Tumor stage | Follow-up (month) | Outcome measure | Expression associates with poor prognosis | Assay | Cut-off value | Location of 8-oxo-dG | Survival analysis | NOS score | Method* |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Li et al. 2012 [22] | China | Hepatocellular carcinoma | 103 | I-IV | 36 | OS | High | IHC | percentage of positive tumor cells | Nuclei | multivariate | 6 | 1 |
| Karihtala et al. 2009 [19] | Finland | Ovarian cancer | 68 | I-IV | 41 | OS | High | IHC | median | Nuclei | multivariate | 6 | 1 |
| Ma-on et al. 2017 [23] | Thailand | Hepatocellular carcinoma | 53 | NA | 80 | OS | High | IHC | IHC score 12 | Nuclei | NA | 5 | 2 |
| Xu et al. 2013 [24] | China | Ovarian cancer | 72 | I-IV | Over 120 | OS, PFS | High | ELISA | Fold change | NA | univariate, multivariate | 8 | 1,2 |
| He et al. 2014 [25] | China | Esophageal cancer | 144 | I-IV | 60 | OS | High | IHC | percentage of positive tumor cells | Nuclei | multivariate | 8 | 1,2 |
| Shen et al. 2007 [26] | USA | Nonsmall-Cell Lung cancer | 99 | I-IV | 82 | OS | High | ELISA | median | NA | multivariate | 7 | 1 |
| Soini et al. 2011 [27] | Finland | Bladder carcinoma | 252 | I-IV | 300 | OS | High | IHC | positive > 5% | Nuclei | NA | 6 | 2 |
| Dziaman et al. 2014 [20] | Poland | Colorectal cancer | 79 | I-IV | 100 | OS | High | LCEC | median | NA | NA | 6 | 2 |
| Jakovcevic et al. 2015 [21] | Croatia | Breast cancer | 145 | I-IV | 112 | OS, DFS | Low | IHC | percentage of positive tumor cells | Nuclei | univariate multivariate | 6 | 1 |
| Pylväs et al. 2011 [29] | Finland | Ovarian cancer | 84 | I-IV | Over 125 | OS | High | IHC, ELISA | percentage of positive tumor cells for IHC. 140 pg/mL for ELISA | NA | univariate multivariate | 6 | 2 |
| Aman et al. 2017 [30] | Japan | Ovarian cancer | 95 | I-IV | 208 | OS | High | IHC | percentage of positive tumor cells | Nuclei | univariate | 6 | 1 |
| Matosevic et al. 2015 [31] | Croatia | Colorectal cancer | 138 | I-IV | 169 | OS | High | IHC | percentage of positive tumor cells | Cytoplasm | multivariate | 7 | 1 |
| Matsumoto et al. 2003 [32] | Japan | Hepatocellular carcinoma | 73 | NA | Over 60 | CSS, RFS | High | IHC | percentage of positive tumor cells | NA | univariate multivariate | 8 | 1,2 |
| Hintsala et al. 2016 [33] | Finland | Melanoma | 121 | NA | Over 150 | CSS | Low | IHC | NA | Nuclei | multivariate | 6 | 1 |
| Murtas et al. 2010 [34] | Italy | Melanoma | 46 | I-II | 60 | OS | High | IHC | percentage of positive tumor cells | Nuclei | multivariate | 8 | 1 |
| Sheridan et al. 2009 [35] | Ireland | Colorectal cancer | 113 | I-IV | 80 | OS | High | IHC | NA | Nuclei | multivariate | 6 | 1 |
| Karihtala et al. 2011 [36] | Finland | Breast cancer | 79 | I-III | 60 | CSS | Low | IHC | NA | Nuclei | univariate multivariate | 6 | 2 |
| Maki et al. 2007 [37] | USA | Hepatocellular carcinoma | 30 | I-II | NA | DFS | High | IHC | percentage of positive tumor cells | NA | multivariate | 6 | 1 |
| Pylväs-Eerola et al. 2015 [38] | Finland | Ovarian cancer | 105 | I-IV | NA | OS, DFS | High | ELISA | median | NA | multivariate | 6 | 1,2 |
| Miyake et al.2004 [39] | Japan | Renal cell carcinoma | 72 | I-IV | NA | CSS | High | ELISA | mean plus one standard deviation | NA | multivariate | 6 | 1 |
| Sova et al. 2010 [40] | Finland | Breast cancer | 150 | I-IV | NA | CSS | Low | IHC | percentage of positive tumor cells | Nuclei | multivariate | 6 | 1 |
OS overall survival, DFS disease free survival, PFS progression free survival, RFS recurrence free survival, CSS cancer specific survival, NOS Newcastle-Ottawa Scale, IHC Immunohistochemistry, ELISA Enzyme-linked immunosorbent assay, LCEC Liquid chromatography electrochemistry, NA not available
*1 denoted as obtaining HRs directly from publications; 2 denoted as HRs were extracted and calculated from Kaplan-Meier curves