Table 1 Characteristics and unadjusted data of included studies
Study | Country (Ethnicity) | Form of disease | Cases/Control | HWE | Smoking status | Genotyping methods | |||
|---|---|---|---|---|---|---|---|---|---|
Sample size | Genotype distribution | ||||||||
rs689466 (−1195G > A) |  | GG | GA | AA |  |  |  | ||
 Chiang 2008 | China (Asian) | OSCC | 368/441 | 80/114 | 187/235 | 101/92 | Yes | Mixed | PCR-RFLP |
 Peters 2009 | Netherlands (Caucasian) | HNSCC | 431/438 | 275/260 | 134/163 | 22/15 | Yes | Mixed | PCR |
 Mittal 2010 | India (Asian) | OSCC | 193/137 | 3/5 | 57/32 | 133/100 | Yes | Smokers | PCR-RFLP |
 Chang 2013 | China (Asian) | HNSCC | 313/295 | 93/90 | 146/148 | 74/57 | Yes | Mixed | Taqman |
 Niu 2014 | China (Asian) | HNSCC | 259/1035 | 61/222 | 126/542 | 72/271 | Yes | Mixed | Taqman |
OSCC | 140/1035 | 44/222 | 80/542 | 25/271 | Yes | Mixed | Taqman | ||
LSCC | 90/1035 | 17/222 | 46/542 | 27/271 | Yes | Mixed | Taqman | ||
rs5275 (8473 T > C) |  | TT | TC | CC |  |  |  | ||
 Campa 2007 | European (multicenter) | HNSCC | 553/711 | 252/313 | 237/321 | 44/77 | Yes | Mixed | TaqMan |
OSCC | 252/711 | 113/313 | 117/321 | 22/77 | Yes | Mixed | TaqMan | ||
LSCC | 281/711 | 139/313 | 120/321 | 22/77 | Yes | Mixed | TaqMan | ||
 Mittal 2010 | India (Asian) | OSCC | 135/59 | 74/24 | 53/34 | 8/1 | No | Smokers | PCR-RFLP |
 Chang 2013 | China (Asian) | HNSCC | 313/295 | 209/199 | 89/86 | 15/10 | Yes | Mixed | Taqman |
 Niu 2014 | China (Asian) | HNSCC | 258/1032 | 177/691 | 72/316 | 9/25 | Yes | Mixed | Taqman |
OSCC | 168/1032 | 118/691 | 45/316 | 5/25 | Yes | Mixed | Taqman | ||
LSCC | 90/1032 | 59/691 | 27/316 | 4/25 | Yes | Mixed | Taqman | ||
rs20417 (−765G > C) |  | GG | GC | CC |  |  |  | ||
 Lin 2008 | China (Asian) | OSCC | 297/280 | 193/107 | 104/173 | 0/0 | Yes | Mixed | PCR–RFLP |
 Chiang 2008 | China (Asian) | OSCC | 178/205 | 136/166 | 42/39 | 0/0 | Yes | Mixed | PCR–RFLP |
 Peters 2009 | Netherlands (Caucasian) | HNSCC | 428/433 | 321/321 | 99/99 | 8/13 | Yes | Mixed | PCR |
 Mittal 2010 | India (Asian) | OSCC | 176/96 | 92/41 | 78/49 | 6/6 | Yes | Smokers | PCR–RFLP |
 Lakshmi 2012 | India (Asian) | OSCC | 150/150 | 110/142 | 28/6 | 12/2 | No | Mixed | PCR–RFLP |