Table 1.

Characteristics of the included studies (n = 46)

Study author	Year of publication	Type of study	Country of origin	Type of family history	Study period (start-end)	Type of outcome	Nos quality scale
Arafa et al[33]	2011	Case control	Jordan	FDR	2008-2009	Secondary	6
Bener et al[34]	2010	Case control	Qatar	FDR	2003-2008	Primary	7
Bonelli et al[35]	1988	Case control	Italy	FDR	1980-1986	Primary	4
Castiglione et al[36]	2012	Case control	Italy	FDR	1995-2009	Primary	4
Centonze et al[37]	1993	Case control	Italy	FDR	1987-1989	Primary	8
Crockett et al[38]	2012	Case control	United States	FDR	2001-2006	Secondary	7
Emami et al[39]	2015	Case control	Iran	FDR	N/A	Secondary	5
Fernandez et al[40]	2002	Case control	Italy	FDR	1985-1992	Secondary	5
Freedman et al[41]	1996	Case control	United States	FDR	1982-1992	Secondary	6
Fuchs (health professional cohort) et al[42]	1994	Prospective	United States	FDR	1986-1992	Primary	3
Fuchs (nurse health cohort)	1994	Prospective	United States	FDR	1982-1990	Primary	3
Grosso et al[43]	2014	Case control	Italy	Unclear	2000-2012	Secondary	7
Guo et al[44]	2010	Case control	China	At least one FDR or two or more SDR	2007	Secondary	7
Huang et al[45]	2004	Case control	Japan	FDR	1988-1998	Secondary	2
Ibáñez-sanz et al[46]	2017	Case control	Spain	FDR, SDR, TDR	2008-2013	Secondary	7
Il'yasova et al[47]	2003	Case control	United States	Unclear	1996-2000	Secondary	7
Jia et al[20]	2007	Case control	China	FDR	2003-2005	Secondary	7
Jo et al[48]	2012	Case control	South Korea	Unclear	2004-2007	Secondary	3
Kampman et al[49]	2000	Case control	United States	FDR	1991-1994	Secondary	6
Kim et al[50]	2009	Case control	South Korea	FDR	2001-2004	Secondary	4
Kotake et al[51]	1995	Case control	Japan	FDR	1992-1994	Primary	6
Kune et al[52]	2009	Case control	Australia	FDR	1980-1981	Primary	7
La vecchia et al[53]	1996	Case control	Italy	FDR	1985-1992	Secondary	4
Le merchand et al[54]	1999	Case control	United States	FDR	1987-1991	Secondary	8
Lee et al[55]	2014	Retrospective	Sweden	FDR: Sibling only	1958-2009	Primary	5
Lohsoonthorn et al[26]	1995	Case control	Thailand	FDR: Parents only	N/A	Primary	7
Mahmoudi et al[56]	2014	Case control	Iran	Unclear	2009-2012	Secondary	4
Mahmoudi et al[57]	2016	Case control	Iran	Unclear	2008-2012	Secondary	4
Minami et al[58]	2003	Case control	Japan	FDR	1997-2001	Secondary	5
Morois et al[59]	2014	Prospective	France	FDR	1990-2008	Secondary	4
Newcomb et al[60]	1999	Case control	United States	FDR	1990-1991	Primary	7
Otani et al[61]	2006	Case control	Japan	Unclear	1990-2003	Secondary	7
Pou et al[61]	2012	Case control	Argentina	FDR	2006-2010	Secondary	7
Rennert et al[62]	2010	Case control	Israel	FDR	N/A	Secondary	5
Rosenberg et al[63]	1998	Case control	United States	FDR	1992 -1994	Secondary	8
Russo et al[64]	1998	Case control	Italy	Unclear	1992-1996	Secondary	4
Samadder et al[65]	2016	Case control	United States	FDR	2000-2010	Secondary	7
Schoen et al[66]	2015	Prospective	United States	FDR	1993-2001	Primary	5
Senda-nakagawa herpacc (i) et al[67]	2017	Case control	Japan	FDR	1988-2000	Secondary	5
Senda-nakagawa herpacc (ii)	2017	Case control	Japan	FDR	2001-2005	Secondary	5
Seow et al[68]	2002	Case control	China	FDR	1999-2000	Secondary	4
Shang et al[69]	2016	Case control	Australia, Canada, United States	FDR	1997-2012	Secondary	6
Sun et al[70]	2012	Case control	Canada	Unclear	1997-2003	Secondary	7
Turati et al[71]	2013	Case control	Italy, Switzerland	FDR	1991-2009	Primary	3
Weigl et al[72]	2016	Case control	Germany	FDR	2003-2014	Secondary	7
Wells et al[73]	2014	Case control	United States	FDR: colon cancer only (not rectal)	1993-1996	Secondary	5

FDR: First-degree relative; SDR: Second degree relative; TDR: Third degree relative; NOS: Newcastle Ottawa scale.