Association between esophageal cancer risk and EPHX1 polymorphisms: A meta-analysis

Table 1 Characteristics of the studies included in the meta-analysis

Study	Year	Country	Ethnicity	Cases	Controls	Source of controls	Type of cancer	DNA source
Dura et al[9]	2012	The Netherlands	Caucasian	349	581	PB	ESCC and EADC	Blood and tissue samples
Ihsan et al[10]	2010	India	Asian	142	185	PB	ESCC	Blood samples
Jain et al[11]	2008	India	Asian	107	320	PB	ESCC	Blood samples
Casson et al[16]	2006	Canada	Caucasian	56	95	HB	EADC	Blood samples
Lin et al[13]	2006	China	Asian	145	352	PB	ESCC	Blood samples
Zhang et al[14]	2003	China	Asian	257	252	HB	ESCC	Blood samples
Wang et al[15]	2003	China	Asian	62	38	PB	ESCC	Tissue samples

EPHX1: Microsomal epoxide hydrolase; ESCC: Esophageal squamous cell carcinoma; EADC: Esophageal adenocarcinoma; PB: Population-based controls; HB: Hospital-based controls.