Table 1.

Characteristics of eligible studies included in the meta-analysis

Study	Cancer type	Country	Ethnicity	Year	Genotyping method	Case/control	Case			Control			HWE
							CC	CT	TT	CC	CT	TT
Rollin et al. [16]	Lung cancer	French	Caucasian	2007	PCR-RFLP	89/90	69	18	2	67	21	2	0.82
Zhou et al. [17]	Lung cancer	China	Asian	2004	PCR-RFLP	770/777	506	230	34	425	313	39	0.05
Zhou et al. [18]	Head & neck cancer	China	Asian	2007	Sequencing	580/478	397	159	24	281	167	30	0.44
Ozgen et al. [19]	Head & neck cancer	Turkey	Caucasian	2008	PCR-RFLP	42/147	23	19	0	99	51	7	0.89
Yu et al. [20]	Esophageal cancer	China	Asian	2004	PCR-RFLP	527/777	323	179	25	425	313	39	0.05
Sun et al. [21]	Esophageal cancer	China	Asian	2009	PCR-RFLP	335/624	222	100	13	408	187	29	0.21
Zhai et al. [22]	Hepatocellular carcinoma	China	Asian	2007	Sequencing	431/478	229	167	35	281	167	30	0.44
Sun et al. [15]	Gastric cancer	China	Asian	2009	PCR-RFLP	257/624	185	63	9	408	187	29	0.21
Li et al. [23]	Ovarian cancer	China	Asian	2008	PCR-RFLP	246/324	164	69	13	181	127	16	0.29
Park et al. [24]	Colorectcal cancer	Korea	Asian	2010	PCR-RFLP	333/318	180	128	25	189	110	19	0.58
Sharma et al. [25]	Gallbladder cancer	India	Asian	2012	PCR-RFLP	410/230	290	112	8	188	40	2	0.94
Gonzalez et al. [26]	Lung cancer	Spain	Caucasian	2012	PCR-RFLP	879/803	596	206	14	465	125	20	0.002
Srivastava et al. [27]	Prostate cancer	India	Asian	2012	PCR-RFLP	190/200	132	50	8	135	60	5	0.58
Srivastava et al. [28]	Bladder cancer	India	Asian	2013	PCR-RFLP	200/200	122	69	9	135	60	5	0.58
Yari et al. [29]	Breast cancer	Iran	Asian	2014	PCR-RFLP	98/135	70	28	0	80	52	3	0.09
Mahmoud et al. [14]	Lymphoma	Egypt	Caucasian	2014	PCR-RFLP	100/100	70	23	7	85	15	0	0.42