Table 1 Studies included

Noura et al. [7]

1985–2006

Japan

2299

1.3 %

(0.8–1.8 %)

YES

Clinical

Diagnosed CRC

Suzuki et al. [8]

1979–2010

Japan

5345

2.6 %

(2.2–3.1 %)

-

Clinical

Diagnosed CRC

Hugen et al.^b [9]

1991–2010

Netherlands

5817

0.9 %

(0.7–1.2 %)

NO

Autopsy

Diagnosed CRC

Tan et al. [10]

1995–2003

Singapore

4378

0.6 %

(0.4–0.9 %)

YES

Clinical

Diagnosed CRC

Mongan et al. [11]

1984–2006

USA

1620

2.3 %

(1.7–3.3 %)

YES

Clinical

Diagnosed CRC

Jung M et al. [12]

1995–2008

Korea

8732

1.5 %

(1.2–1.7 %)

YES

Clinical

Diagnosed CRC

Pramateftakis et al. [13]

1990–2009

Greece

670

0.7 %

(0.2–1.7 %)

YES

Clinical

Diagnosed CRC

Jiang et al. [14]

1991–2010

China

8220

0.7 %

(0.6–0.9 %)

-

Clinical

Diagnosed CRC

Tevlin et al. [15]

1988–2012

Ireland

4219

0.3 %

(0.1–0.5 %)

-

Clinical

Diagnosed CRC

Tanriverdi et al. [16]

2001–2012

Turkey

4864

2.7 %

(2.3–3.2 %)

-

Clinical

Diagnosed CRC

Temple et al. [17]

1959–1979

USA

999

2.9 %

(2.0–4.1 %)

YES

Autopsy

Diagnosed CRC

Naito et al. [18]

1967–1992

Japan

778

1.9 %

(1.1–3.2 %)

YES

Clinical

Diagnosed CRC

Hammoud et al. [19]

1980–1994

USA

8632

1.7 %

(1.5–2.0 %)

YES

Clinical

Diagnosed CRC

Ko et al. [20]

1970–1996

Taiwan

7153

0.7 %

(0.6–1.0 %)

-

Clinical

Diagnosed CRC

Zorrilla et al. [21]

1996–2000

Spain

378

2.4 %

(1.1–4.5 %)

YES

Clinical

Diagnosed CRC

Schouten et al. [22]

1986–1998

Netherlands

720

1.4 %.

(0.7–2.5 %)

-

Clinical

Diagnosed CRC

Barnholtz-Sloan et al. [23]

1973–2001

USA

42,817

1.8 %

(1.7–2.0 %)

YES

Register

Diagnosed CRC

Kim et al. [24]

1987–2009

Korea

4350

1.1 %

(0.8–1.4 %)

-

Clinical

Diagnosed CRC^d

Sundermeyer et al. [25]

1993–2002

USA

1020

3.2 %

(2.2–4.5 %)

-

Clinical

mCRC

Yeager et al. [26]

2008–2012

USA

918

4.0 %

(2.9–5.5 %)

-

Clinical

mCRC

Chyun et al. [27]

1977–1989

USA

78

23.0 %

(14.3–34.0 %)

YES

Clinical

mCRC

Patanaphan et al. [28]

1979–1982

USA

163

3.0 %

(0.7–6.2 %)

YES

Clinical

mCRC

Tran et al. [29]

1996–2009

Australia and USA

524

5.15 %

(3.4–7.4 %)

-

Clinical

mCRC

Hess et al. [30]

1994–1997

USA

984

0.7 %^c

(0.3–1.5 %)

-

Clinical

mCRC

Tie et al. [31]

1999–2009

Australia

46

-

-

Clinical

mCRC

Khattak et al. [32]

2006–2011

Australia

2006

-^e

NO

Clinical

mCRC^e.

Kemeny et al. [33]

2003–2013

USA

169

5.0 %

(2.5–9.9 %)

NO

Clinical

Liver metastasectomy + chemotherapy

Yoshidome et al. [34]

1985–2001

Japan

207

4.0 %

(1.7–7.5 %)

YES

Clinical

Liver metastasectomy

de Jong et al. [35]

1982–2008

USA

1669

1.3 %

(0.8–2.0 %)

-

Clinical

Liver metastasectomy

Byrne et al. [36]

1987–2009

UK

1304

4.0 %

(3.0–5.2 %)

YES

Clinical

Liver metastasectomy

Higashiyama et al. [37]

1981–2001

Japan

100

13.0 %

(7.1–21.2 %)

YES

Clinical

Pulmonary metastasectomy

Hugen et al.^b [9]

1996–1999

Netherlands

1530

1.1 %

(0.6–1.8 %)

-

Clinical

Rectal cancer

Chiang et al. [38]

2002–2006

Taiwan

884

-^f

YES

Clinical

Rectal cancer with T3 and T4 who had not received neoadjuvant therapy

Weiss et al. [39]

1944–1984

Multiple

1541

2.5 %

(1.8–3.4 %)

-

Autopsy

Colon cancer

Cascino et al. [40]

1977–1980

USA

1006

4.0 %

(2.9–5.4 %)

YES

Clinical

Colon cancer

Takagawa et al. [41]

1992–2003

Japan

638

1.3 %

(0.5–2.5 %)

YES

Clinical

Verified radical resected stages 1–3 tumor

van Gestel et al. [42]

2003–2008

Netherlands

5671

1.11 %

(0.9–1.4 %)

Yes

Register

Intended curatively treated primary cancer stages 1–3.

Tokoro et al. [43]

1998–2010

Japan

1364

1.8 %

(1.2–2.7 %)

YES

Clinical

Surgically treated for primary cancer and/or metastases

Scartozzi et al. [44]

1995–2005

Italy

99

-

-

Clinical

Both primary and metastases removed

Damiens et al. [4]

2000–2009

Canada

48

-

YES

Clinical

BM

Kruser et al. [45]

1994–2005

USA

49

-

-

Clinical

BM

Smedby et al. [46]

1987–2006

Sweden

1001

-

YES

Register

BM

Fokas et al. [47]

1996–2007

Germany

78

-

YES

Clinical

BM

Magni et al. [48]

2003–2013

Italy

41

-

Yes

Clinical

BM

Farnell et al. [49]

1976–1993

USA

150

-

YES

Clinical

BM

Kye et al. [50]

1997–2006

Korea

39

-

-

Clinical

BM and survived more than a month after BM diagnosis

Beak et al. [51]

2001–2009

Korea

118

-

-

Clinical

BM treated with WBRT, SRS, or surgery

Nieder et al. [52]

1983–2008

Norway

35

-

YES

Clinical

BM treated with WBRT

Bartelt et al. [53]

1985–2000

Germany

47

-

YES

Clinical

BM treated with WBRT

Heisterkamp et al. [54]

1989–2008

Germany

53

-

-

Clinical

BM treated with WBRT

Matsunaga et al. [55]

1992–2008

Japan

152

-

YES

Clinical

BM less than 3 cm and treated with SRS

Schoeggl et al. [56]

1993–1996

Austria

35

-

-

Clinical

BM treated with SRS

Wronski et al. [57]

1974–1993

USA

73

-

YES

Clinical

BM treated neurosurgically

Fowler et al. [58]

1999–2007

Australia

32

-

YES

Clinical

BM treated neurosurgically

Maglio et al. [59]

1999–2013

Italy

53

-

Yes

Clinical

BM treated neurosurgically

Mege et al. [60]

1998–2009

France

28

-

YES

Clinical

BM treated neurosurgically

Taher et al. [61]

1990–2009

Sweden

37

-

-

Clinical

BM treated neurosurgically

D’Andrea et al. [62]

1960–2000

Italy

44

-

-

Clinical

Single BM neurosurgically treated

Simonova et al. [63]

1992–1998

Czech republic

30

-

-

Clinical

Single BM radiosurgically treated

Onodera et al. [64]

1979–1998

Japan

1077

-

-

Clinical

Criteria unknown