Table 1.

Main characteristics of all studies included in the meta-analysis

Authors	Year	Country	Ethnicity	Control Source	Cancer Type	Genotyping Method	Genotype distribution (case/control)			HWE (P)
							Asp/Asp	Asp/Asn	Asn/Asn
Zhang et al [18]	2014	China	Chinese	HB	ESCC	PCR-RFLP	349/354	55/50	1/1	0.579
Huang et al [19]	2012	China	Chinese	HB	ESCC	PCR-RFLP	171/298	42/60	0/0	0.084
Wang et al [20]	2012	China	Chinese	PB	ESCC	PCR-RFLP	349/354	55/50	1/1	0.580
Li et al [21]	2012	China	Chinese	HB	ESCC	PCR-RFLP	342/351	56/47	2/2	0.754
Wu et al [22]	2010	China	Chinese	PB	ESCC	PCR-Taq	206/212	28/22	1/1	0.602
Pan et al [23]	2009	America	European	HB	ESCC	PCR-Taq	137/201	163/185	43/48	0.581
Zhou et al [24]	2007	China	Chinese	PB	ESCC	PCR-RFLP	279/528	46/82	2/2	0.527
Ye et al [25]	2006	Sweden	European	PB	ESCC	PCR-RFLP	30/176	41/237	10/57	0.093
Yu et al [26]	2004	China	Chinese	HB	ESCC	PCR-RFLP	121/136	14/16	0/0	0.493
Xing et al [27]	2003	China	Chinese	HB	ESCC	PCR-RFLP	286/338	38/45	1/0	0.222
Xing et al [28]	2002	China	Chinese	HB	ESCC	PCR-RFLP	381/461	49/62	3/1	0.467
Pan et al [23]	2009	America	European	HB	EADC	PCR-Taq	16/201	20/185	1/48	0.581
Ye et al [25]	2006	Sweden	European	PB	EADC	PCR-RFLP	31/176	51/237	14/57	0.093
Tse et al [29]	2008	Canada	Mixed	HB	EADC	PCR-Taq	117/199	150/206	43/49	0.690
Liu et al [30]	2007	America	European	HB	EADC	PCR-RFLP	75/144	92/160	16/32	0.190

HWE, Hardy-Weinberg equilibrium; P<0.05 was considered statistically significant; PCR-RFLP, polymerase chain reaction-restriction fragment length polymorphism; ESCC, Esophageal Squamous Cell Carcinoma; EADC, Esophageal Adenocarcinoma; HB, Hospital-based; PB, Population-based; P, value for HDW.