Table 1. Demographic and clinical characteristics of included studies.

Study	Country	Cases	Controls	Analytical Method	Mutation Gene	Mutation Site	NOS
Burmer 1991	UK	UC-CRC	S-CRC	PCR	KRAS	Codon 12	7
Bell 1991	USA	UC-CRC or dysplasia	S-CRC	PCR	KRAS	Codon 12	9
Taylor 1993	UK	IBD-CRC	S-CRC	IHC positive	TP53	NA	9
Rashid 1997	USA	CD associated adenocarcinomas	S-CRC	≥50% IHC positive/PCR	TP53/KRAS	NA/codon 12, 13	7
Lashner 1999	USA	UC-CRC	UC	≥5% IHC positive	TP53	NA	7
Walsh 1999	USA	UC-CRC or dysplasia	S-CRC	IHC positive	TP53	NA	9
Reeves 2004	UK	IBD-CRC	S-CRC	PCR	TP53/KRAS	NA/codon 12	7
Maia 2005	Portugal	IBD-CRC or dysplasia	IBD	PCR-SSCP	TP53	Exon 6, 7	7
Bossard 2007	France	IBD-CRC	IBD	PCR	KRAS	Codon 12, 13	7
Nathanson 2008	USA	CD dysplasia	CD	Dark-brown IHC stain	TP53	NA	7
Laurent 2011	France	IBD-CRC	S-CRC, IBD	≥10% IHC positive	TP53	NA	7
Sanchez 2011	USA	UC-CRC	S-CRC	PCR	TP53/KRAS	Exon 4, 8/ codon 12, 13	9
Olaru 2012	USA	IBD-CRC	S-CRC	PCR	KRAS	NA	7
Shivakumar 2012	India	IBD-CRC	S-CRC, UC	PCR	TP53/KRAS	Exon 4-8/ codon 12, 13	7
Kisiel 2013	USA	IBD-CRC	IBD	PCR	TP53/KRAS	NA	9
Ottessen 2015	Norway	UC-CRC	UC	≥5% IHC positive	TP53	NA	7
Johnson 2016*	USA	IBD-CRC	IBD	PCR	KRAS	NA	9
Lennerz 2016	USA	CD-CRC	S-CRC	PCR	KRAS	NA	7
Yaeger 2016	USA	IBD-CRC	S-CRC	PCR	TP53/KRAS	NA	7

IBD: inflammatory bowel disease; UC: ulcerative colitis; CD: Crohn’s disease; CRC: colorectal cancer; PCR: polymerase chain reaction; SSCP: single-strand conformation polymorphism; S-CRC: sporadic colorectal cancer; NOS: Newcastle-Ottawa Scale.

*The study by Johnson et al 2016 contained two independent phases, and the data of one cohort phase was first presented in 2014