Table 2. Characteristics of included studies.

Author and year	SOC	Ethnicity	Case			Control			NOS
			CC	CT	TT	CC	CT	TT
Nimptsch (2015)	PB	Mixed	358	292	71	302	342	81	8
Yang (2011)	PB	Asians	72	197	152	40	111	67	6
Slattery (2011) (CC)	PB	Mixed	700	659	163	882	845	157	6
Slattery (2011) (RC)	PB	Mixed	295	325	79	406	403	92	7
Ognjanovic (2010)	PB	Mixed	55	119	96	146	250	140	7
Tsilidis (2009)	PB	Mixed	99	83	24	167	156	51	6
Siemes (2006) (CRC)	PB	Caucasians	78	92	19	2584	2595	588	7

Abbreviations: CC, colon cancer; PB, population-based; RC, rectal cancer.