Peroxisome proliferator-activated receptor-γ 34C>G polymorphism and colorectal cancer risk: A meta-analysis

Table 1 Study characteristics

No.	Ref.	Yr	Country	Number of cases					Number of controls					34G allele fre-quency in control	P1
				CC	CG	GG	Total	CG + GG	CC	CG	GG	Total	CG + GG
1	Landi et al[5]	2003	Spain (W, E)	311	46	3	360	49	243	61	5	309	66	0.11	0.773
2	Gong et al[2]	2005	USA (W)	129	30	4	163	34	153	52	7	212	59	0.16	0.743
3	Murtaugh et al[6]	2005	USA (W)	1840	-	-	2371	531	2283	-	-	2972	689	-	-
4	Jiang et al[4]	2005	India (A)	240	57	4	301	61	230	57	4	291	61	0.11	1.000
5	Siezen et al[1]	2006	Netherlands (W, E)	160	40	1	201	41	325	71	2	398	73	0.09	0.783
6	Koh et al[7]	2006	Singapore (A)	345	-	-	362	17	1075	-	-	1164	89	-	-
7	Gunter et al[8]	2006	USA (W)	153	41	4	198	45	146	37	1	184	38	0.11	0.838
8	Theodoropoulos et al[9]	2006	Greek (W, E)	164	48	10	222	58	118	70	12	200	82	0.24	0.950
9	Vogel et al[10]	2007	Denmark (W, E)	252	96	7	355	103	550	190	13	753	203	0.14	0.816

¹P value for Hardy-Weinberg equilibrium (HWE) for peroxisome proliferator-activated receptor-γ (PPAR-γ) 34C>G polymorphism among controls. W: Western country; E: European country; A: Asian country; -: No data was shown in reference.