Xeroderma pigmentosum group D polymorphisms and esophageal cancer susceptibility: A meta-analysis based on case-control studies

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

Ref.	Country	Ethnicity	Control source	Cancer type	Genotype distribution (case/control)						P for HWE
					Asp312Asn			Lys751Gln
					Asp/Asp	Asp/Asn	Asn/Asn	Lys/Lys	Lys/Gln	Gln/Gln	Asp312Asn	Lys751Gln
Xing et al[21] 2002	China	Chinese	PB	ESCC	381/461	49/62	3/1	367/451	63/70	3/3	0.47	0.87
Xing et al[22] 2003	China	Chinese	PB	ESCC	286/338	38/45	1/0	278/331	44/49	3/3	0.22	0.43
Yu et al[23]2004	China	Chinese	HB	ESCC	121/136	14/16	0/0	108/133	16/17	11/2	0.49	0.11
Casson et al[24] 2005	Canada	Caucasian	HB	EADC	-	-	-	31/34	21/46	4/15	-	0.93
Ye et al[25]2006	Sweden	Swedish	PB	EADC	31/176	51/237	14/57	27/198	51/203	18/71	0.09	0.11
				ESCC	30/176	41/237	10/57	23/198	44/203	14/71	0.09	0.11
Sobti et al[26] 2007	India	Indian	HB	ESCC	-	-	-	52/63	61/77	7/20	-	0.64
Doecke et al[27] 2008	Australia	Mixed	PB	EADC	-	-	-	108/575	123/588	32/174	-	0.22
Ferguson et al[28] 2008	Ireland	Caucasian	PB	EADC	-	-	-	80/91	94/121	34/35	-	0.61
Tse et al[19] 2008	United States	Mixed	HB	EADC	117/199	150/206	43/49	104/193	159/208	49/52	0.69	0.72
Pan et al[29] 2009	United States	Caucasian	HB	ESCC	16/201	20/185	1/48	17/187	18/216	3/53	0.58	0.43
				EADC	137/201	163/185	43/48	137/187	153/216	56/53	0.58	0.43
Zhai et al[30] 2009	China	Chinese	HB	ESCC	-	-	-	167/148	31/51	2/1	-	0.12
Huang et al[29] 2012	China	Chinese	HB	ESCC	171/298	42/60	0/0	150/274	55/79	8/5	0.08	0.80
Li et al[31] 2013	China	Chinese	PB	ESCC	342/351	56/47	2/2	283/321	105/73	12/6	0.75	0.43

PB: Population-based study; HB: Hospital-based study; ESCC: Esophageal squamous cell carcinoma; EADC: Esophageal adenocarcinoma; HWE: Hardy-Weinberg equilibrium.