Table 1. Overview of included studies.

						AJCC stage
Author	Year	Country	Study period	Site of cancer	No. of patients	I	II	III	IV	Newcastle–Ottawa Score
Hase	1993	Japan	1970–1985	CR	663	✓	✓	✓		7
Ueno	2002	Japan	1981–1994	R	437			✓		7
Okuyama	2003	Japan	1985–1997	C	196		✓	✓		8
Okuyama	2003	Japan	1985–1997	R	83		✓	✓		7
Ueno	2004	Japan	1960–1980	R	1114	✓	✓	✓		9
Prall	2005	Germany	1994–1999	CR	182	✓	✓			8
Wang	2005	China	1969–2002	CR	159	✓		✓		8
Yasuda	2007	Japan	NA	CR	86	✓		✓		7
Kanazawa	2008	Japan	1996–2001	CR	133		✓	✓	✓	7
Nakamura	2008	Japan	1986–1998	C	200		✓			7
Yamauchi	2008	Japan	1991–2001	CR	164	✓		✓		8
Lugli	2009	Switzerland	1987–1996	CR	273	✓	✓	✓		7
Ogawa	2009	Japan	1995–2003	CR	83	✓		✓		8
Wang	2009	Ireland	1990–2004	CR	128		✓			9
Homma	2010	Japan	2000–2007	R	65	✓		✓		6
Kajiwara	2010	Japan	1985–2005	CR	244	✓		✓		8
Komori	2010	Japan	1990–2004	CR	111	✓		✓		8
Tateishi	2010	Japan	1992–2005	CR	322	✓		✓		8
Akishima-Fukasawa	2011	Japan	1989–2009	CR	111	✓		✓		7
Reggiani Bonetti	2011	Italy	1989–2004	CR	95	✓		✓		6
Betge	2012	Austria	1984–2005	CR	110		✓			8
Nakadoi	2012	Japan	1981–2008	CR	499	✓		✓		8
Sert Bektas	2012	Turkey	2003–2007	CR	73	✓	✓	✓		6
Wada	2013	Japan	1995–2005	CR	120	✓		✓		8
Zlobec	2012	Switzerland	1987–1996	CR	127	✓	✓	✓		8
Nishida	2014	Japan	2000–2011	CR	265	✓		✓		8
Huh	2014	Korea	2007–2009	CR	543	✓		✓		8
Lai	2014	China	1999–2007	C	135		✓			6
Ryu	2014	Korea	2003–2012	CR	179	✓		✓		8
Gilardoni	2015	Italy	2006–2009	C	196	✓	✓			8
Macias-Garcia	2015	Spain	2000–2011	CR	97	✓				8
Tristante	2015	Spain	2011–2014	CR	58		✓	✓		4
Barresi	2016	Italy	NA	CR	82		✓			7
Miyachi	2016	Japan	2001–2014	CR	653	✓				7

Abbreviations: C=colon only; CR=colon and rectum; NA=not available; R=rectum only.