Table 1. Basic characteristics of the included studies.

Study	Country	Patients	Methods	Primary Aim	Methylation site	CHFR expression
Cleven et al. 2014 [24]	Netherland	468	MSP	Determine the prognostic role of CHFR in stage II microsatellite stable colorectal cancer	Promoter, CpG	-
Tanaka et al. 2011 [25]	USA	82	Pyrosequencing/Immunochemistry	Study the association of CHFR promoter methylation with disease recurrence in advanced colon cancer	Promoter, CpG	+
Leong et al. 2011 [26]	UK	70	MSP	Investigate methylation profile of rectal cancer and identify novel markers	Promoter, CpG	-
Joensuu et al. 2008 [27]	Finland	148	MS-MLPA	Study epigenetic signatures of familial cancer in different tumor types and family categories.	Promoter, CpG	-
Derks et al. 2006 [28]	Netherlands	36	MSP	Study the timing of promoter methylation and relationship with mutations and chromosomal alterations in colorectal carcinogenesis.	Promoter, CpG	-
Morioka et al. 2006 [29]	Japan	98	MSP/RT-PCR	Study aberrant methylation of CHFR in colorectal cancer	Promoter	-
Brandes et al. 2005 [30]	Netherlands	64	MSP	Study the correlation of CHFR hypermethylation with microsatellite instability phenotype.	Promoter	-

MSP: methylation-specific PCR, MS-MLPA: Methylation-specific multiplex ligation-dependent probe ampliification.