Table 1. Characteristics of studies included in the meta-analysis.
| First Author | Year | Country | Ethnicity | Control | No. of Cases | No. of Controls | Cancer Type | Sample size | Cases | Controls | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| AA | CA | CC | AA | CA | CC | |||||||||
| Liu JM | 2013 | China | Asian | Population Based | 375 | 400 | Prostate Cancer | Large | 103 | 172 | 100 | 110 | 196 | 94 |
| Babar M | 2012 | UK | Caucasian | Population Based | 1070 | 194 | Esophageal Cancer | Large | 178 | 508 | 384 | 36 | 75 | 83 |
| Du B | 2012 | China | Asian | Hospital Based | 150 | 180 | Nasopharyngeal Carcinoma | Small | 34 | 80 | 36 | 40 | 93 | 47 |
| Guo JY | 2012 | China | Asian | Hospital Based | 170 | 160 | Colorectal Cancer | Small | 49 | 85 | 36 | 42 | 76 | 42 |
| Taheri M | 2012 | Iran | Asian | Population Based | 72 | 93 | Breast Cancer | Small | 11 | 32 | 29 | 8 | 45 | 40 |
| Saenz-Lopez P | 2010 | Spain | Caucasian | Population Based | 154 | 500 | Other Types | Large | 19 | 76 | 59 | 73 | 261 | 166 |
| Asefi V | 2009 | Iran | Asian | Hospital Based | 111 | 212 | Other Types | Small | 15 | 53 | 43 | 29 | 101 | 82 |
| Farjadfar A | 2009 | Iran | Asian | Hospital Based | 73 | 97 | Other Types | Small | 13 | 45 | 15 | 11 | 46 | 40 |
| Haghshenas MR | 2009 | Iran | Asian | Population Based | 142 | 311 | Colorectal Cancer | Small | 15 | 72 | 55 | 48 | 144 | 119 |
| Haghshenas MR | 2009 | Iran | Asian | Population Based | 87 | 311 | Other Types | Small | 16 | 40 | 31 | 48 | 144 | 119 |
| Khalili-Azad T | 2009 | Iran | Asian | Population Based | 200 | 206 | Breast Cancer | Small | 33 | 103 | 64 | 33 | 97 | 76 |
| Nong LG | 2009 | China | Asian | Population Based | 250 | 270 | Nasopharyngeal Carcinoma | Large | 71 | 132 | 47 | 68 | 133 | 69 |
| Samsami DA | 2009 | Iran | Asian | Hospital Based | 85 | 158 | Other Types | Small | 12 | 51 | 22 | 26 | 75 | 57 |
| Farhat K | 2008 | Tunisia | African | Population Based | 163 | 164 | Nasopharyngeal Carcinoma | Small | 28 | 94 | 41 | 34 | 77 | 53 |
| Kashef MA | 2008 | Iran | Asian | Population Based | 19 | 103 | Other Types | Small | 3 | 10 | 6 | 16 | 54 | 33 |
| Qi T | 2008 | China | Asian | Hospital Based | 50 | 50 | Cervical Cancer | Small | 28 | 17 | 5 | 9 | 24 | 17 |
| Liu Y | 2007 | China | Asian | Hospital Based | 265 | 280 | Prostate Cancer | Large | 72 | 143 | 50 | 78 | 137 | 65 |
| Nikiteas N | 2007 | Greece | Caucasian | Population Based | 84 | 89 | Colorectal Cancer | Small | 18 | 47 | 19 | 22 | 32 | 35 |
| Vairaktaris E | 2007 | Germany | Caucasian | Population Based | 149 | 89 | Other Types | Small | 28 | 66 | 55 | 22 | 32 | 35 |
| Wei YS | 2007 | China | Asian | Hospital Based | 235 | 250 | Esophageal Cancer | Small | 64 | 123 | 48 | 67 | 124 | 59 |
| Yang HL | 2007 | China | Asian | Population Based | 107 | 80 | Cervical Cancer | Small | 24 | 50 | 33 | 36 | 26 | 18 |
| Pratesi C | 2006 | Italy | Caucasian | Population Based | 89 | 130 | Nasopharyngeal Carcinoma | Small | 21 | 42 | 26 | 23 | 64 | 43 |