Table 1. Characteristics of studies included in meta-analysis.
| First author[Ref] | Year | Country | Ethnicity | Number | Source of controls | Age (mean value) | Genotyping assay | Gender (male %) | |||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Case | Control | Case | Control | Case | Control | ||||||
| Cui [6] | 2015 | China | Asian | 212 | 200 | Population | 52.5 | 54.4 | PCR-RFLP | 59.7% | 51.8% |
| Flego [14] | 2009 | Croatia | Caucasian | 113 | 230 | Population | NA | NA | PCR-RFLP | NA | NA |
| Gu [15] | 2009 | USA | Caucasian | 212 | 211 | Population | NA | NA | ARMS-PCR | NA | NA |
| Gupta [1] | 2008 | India | Asian | 94 | 133 | Population | 50.7 | NA | PCR-RFLP | 80.9% | NA |
| Huang [19] | 2005 | China | Asian | 65 | 65 | Population | 65.0 | 55.0 | PCR-RFLP | 81.5% | 77.0% |
| Kietthubthew [24] | 2010 | Thailand | Asian | 97 | 152 | Population | 67.5 | 69.7 | Taqman PCR | 73.8% | 55.4% |
| Kostic [17] | 2013 | Serbia | Caucasian | 50# | 60 | Population | 69.0# | NA | PCR-RFLP | 70.0%# | NA |
| 50& | 60 | Population | 73.0& | NA | PCR-RFLP | 40.0%& | NA | ||||
| Liu [7] | 2005 | China | Asian | 192 | 146 | Population | 54.1 | 52.0 | PCR-RFLP | 90.1% | 89.0% |
| Oh [23] | 2010 | USA | Caucasian | 75 | 839 | Population | NA | NA | SNPlex assay | NA | NA |
| Rizzato [11] | 2011 | Mixed | Caucasian | 506 | 515 | Hospital | 67.0 | 61.0 | KASPar SNP genotyping | 44.8% | 51.4% |
| Seifart [9] | 2005 | Germany | Caucasian | 40 | 242 | Population | 65.4 | 37.9 | PCR-RFLP | NA | 55.1% |
| Shih [20] | 2006 | China | Asian | 83 | 205 | Population | NA | 62.8 | PCR-RFLP+ sequencing | NA | 66.3% |
| Singh [8] | 2015 | India | Asian | 272 | 185 | Population | 47.7 | 43.1 | PCR-RFLP | 80.5% | 76.8% |
| Skov [13] | 2003 | Denmark | Caucasian | 191 | 107 | Population | 65.9 | 64.6 | PCR-RFLP | 59.2% | 53.3% |
| Sobjanek [12] | 2015 | Poland | Caucasian | 176 | 261 | Population | 68.9 | NA | ARMS-PCR | 46.6% | NA |
| Umar [5] | 2013 | India | Asian | 290 | 311 | Population | 57.0 | 55.0 | ARMS-PCR | 72.8% | 71.1% |
| Welsh [16] | 2011 | USA | Caucasian | 894& | 816 | Population | 58.7& | 61.3 | Taqman PCR | 56.0%& | 59.9% |
| 681* | 816 | Population | 64.1* | 61.3 | Taqman PCR | 63.5%* | 59.9% | ||||
| Whiteman [18] | 2010 | Australia | Caucasian | 207 | 1293 | Population | NA | NA | Sequenom iPLEX | 58.0% | 66.0% |
| Yang [21] | 2011 | China | Asian | 205 | 198 | Population | 49.3 | 48.9 | Taqman PCR | 100.0% | 100.0% |
| Zhang [22] | 2011 | China | Asian | 160 | 160 | NA | NA | NA | PCR-SSP | NA | NA |
Ref: reference; #: OSCC group; &: SBCC group; *: SSCC group; NA: not available; PCR-RFLP: polymerase chain reaction-restriction fragment length polymorphism; ARMS-PCR: amplification refractory mutation system-polymerase chain reaction; Taqman PCR: Taqman polymerase chain reaction; PCR-SSP: Polymerase chain reaction-sequence specific primer.