Glutathione S-transferase M1 polymorphism and esophageal cancer risk: An updated meta-analysis based on 37 studies

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

Ref.	Year	Ethnicity	Country	Source of controls	Genotype distribution
					Case		Control
					Null	Present	Null	Present
Morita et al[49]	1997	Asian	Japan	PB	23	30	55	77
Nimura et al[43]	1997	Asian	China	HB	47	42	63	74
Hori et al[31]	1997	Asian	Japan	PB	41	53	196	232
Lin et al[27]	1998	Asian	China	PB	20	25	21	24
Shao et al[36]	1999	Asian	China	HB	68	40	55	57
van Lieshout et al[30]	1999	Caucasian	The Netherland	PB	17	17	128	119
Tan et al[14]	2000	Asian	China	PB	46	104	76	74
Shi et al[40]	2002	Asian	China	HB	67	31	51	69
Yokoyama et al[15]	2002	Asian	Japan	HB	103	131	321	313
Gao et al[42]	2002	Asian	China	PB	106	35	133	90
Casson et al[48]	2003	Caucasian	Canada	PB	26	19	25	20
Wang et al[50]	2003	Asian	China	PB	27	35	19	19
Wang et al[44]	2004	Asian	China	HB	74	53	44	57
Abbas et al[33]	2004	Caucasian	French	PB	39	29	59	61
Roth et al[51]	2004	Asian	China	Nest	41	90	145	309
Han et al[39]	2005	Asian	China	HB	46	43	48	51
Lu et al[28]	2005	Asian	China	PB	36	68	4	100
Yin et al[35]	2005	Asian	China	HB	69	37	61	45
Casson et al[45]	2006	Caucasian	Canada	HB	34	22	54	41
Jain et al[32]	2006	Asian	India	HB	39	61	51	86
Dong et al[47]	2007	Asian	China	HB	76	44	51	69
Wideroff et al[41]	2007	Caucasian	United States	PB	37	30	121	87
Rossini et al[29]	2007	Caucasian	Brazil	HB	51	74	99	153
Li et al[34]	2008	Asian	China	PB	77	48	55	70
Zendehdel et al[23]	2009	Caucasian	Sweden	PB	85	85	230	239
Ji et al[38]	2010	Asian	China	PB	111	78	98	127
Malik et al[26]	2010	Asian	India	HB	68	67	79	116
Liu et al[24]	2010	Asian	China	PB	54	43	32	65
Moaven et al[12]	2010	Asian	Iran	HB	65	83	58	78
Li et al[16]	2010	Black	Africa	HB	33	206	80	200
Gao et al[37]	2012	Asian	China	HB	22	18	45	35
Chen et al[17]	2012	Asian	China	HB	68	31	90	96
Liu et al[46]	2013	Asian	China	HB	47	63	74	146
Talukdar et al[25]	2013	Asian	India	PB	44	68	40	90
Sharma et al[13]	2013	Asian	India	PB	129	186	139	297
Dura et al[8]	2013	Caucasian	The Netherland	PB	228	204	318	273
Djansugurova et al[18]	2013	Asian	Kazakhstan	PB	72	43	24	76

PB: Population-based study; HB: Hospital-based study.