Table 1. General Information of Included Studies.

Study	Country	Participants	Comparison	Chemotherapy	K-ras mutation	Outcome Measures	Quality*
					detection
Ahnen 1998	USA	Stage II and III	wild type (n=131)	levamisole or 5-FU plus levamisole	PCR-SSCP	3-year and 5-year OS	8 stars
		CRC patients	versus mutant type (n=89)
Bleeker 2001	Netherland	Dukes C CRC	wild type (n=40)	5-FU/lev/leuco or 5-FU/lev	DGGE	3-year and 5-year OS	8 stars
		patients	versus mutant type (n=15)
Ogino 2009	USA	Stage III CRC	wild type (n=330)	5-FU/leucovorin or IFL	Pyrosequencing	3-year and 5-year OS	8 stars
		patients	versus mutant type (n=178)	(irinotecan, 5-FU and leucovorin)		and 2-year DFS
Chang 2011	Korea	Stage II and III	wild type (n=51)	FL or FOLFOX	DNA-sequence	3-year OS and 2-year	8 stars
		CRC patients	versus mutant type (n=15)			DFS
Gnanasampath-	Australia	Dukes’ C	wild type (n=290)	5-FU/levamisole or	PCR-SSCP	3-year and 5-year OS	8 stars
an 2011		patients	versus mutant type (n=138)	5-FU/leucovorin
Hutchins 2011	UK	Stage II and III	wild type (n=524)	5-FU/folinic acid	Pyrosequencing	2-year DFS	8 stars
		CRC patients	versus mutant type (n=260)
Sec 2012	Poland	Unclear	wild type (n=184)	Irinotecan or oxaliplatin-based	PCR-RFLP	3-year and 5-year OS	7 stars
			versus mutant type (n=89)	therapy

^*Quality of studies was assessed, according to “The Newcastle-Ottawa Scale for assessing the quality of non-randomized studies in meta-analyses” standard, by numbers of stars.