Table I.

Characteristics of studies included in the meta-analysis.

A, Studies on the 91T>A polymorphism
First author (ref.)	Year	Country	Ethnicity	Tumor type	Source of controls	Genotype methods
Akkiz (11)	2010	Turkey	Caucasian	Hepatocellular	HB	PCR-RFLP
Chava (12)	2011	India	Asian	Esophageal	NR	PCR
Chen L (13)	2005	China	Asian	Gastric	HB	PCR-RFLP
Chen JY (14)	2007	USA	Caucasian	Colorectal	HB	Direct sequencing
Chen XB (15)	2009	China	Asian	Esophageal	PB	PCR-RFLP
Ewart-Toland (16)	2005a	USA	Mixed	Colorectal	PB	PCR-RFLP
Ewart-Toland (16)	2005b	Scotland	Caucasian	Colorectal	PB	PCR-RFLP
Hienonen (17)	2006	Finland	Caucasian	Colorectal	PB	Direct sequencing
Ju (18)	2006	South Korea	Asian	Gastric	HB	Mass ARRAY
Kimura (10)	2005	Japan	Asian	Esophageal	HB	PCR
Miao (19)	2004	China	Asian	Esophageal	PB	PCR-RFLP
Sang (20)	2012	China	Asian	Esophageal	HB	MALDI-TOF MS
Wang (21)	2007	China	Asian	Esophageal	PB	PCR-RFLP
Webb (22)	2006	UK	Caucasian	Colorectal	PB	Illuminasentric bead array
Zhang (23)	2006	China	Asian	Colorectal	PB	PCR-RFLP
B, Studies on the 169G>A polymorphism
First author (ref.)	Year	Country	Ethnicity	Tumor type	Source of controls	Genotype methods
Chen L (12)	2005	China	Asian	Gastric	HB	PCR-RFLP
Chen JY (13)	2007	USA	Caucasian	Colorectal	HB	Direct sequencing
Ju (17)	2006	South Korea	Asian	Gastric	HB	Mass ARRAY
Kimura (18)	2005	Japan	Asian	Esophageal	HB	PCR

NR, not reported; HB, hospital-based; PB, population-based; MALDI-TOF MS, matrix-assisted laser desorption/ionization time of flight mass spectrometry; PCR-RFLP, polymerase chain reaction-restriction fragment length polymorphism; ref., reference.