Table 1.

Summary of the reviewed articles

Study	Country	Study period	Age of the children (y)	No. of participants		Matching control	Matching variables	Primary outcome	NOS score
				Case	Control
Preston-Martin et al., 1998 [34]	USA, France, Israel, and Europe	1976-1994	0-19	1051	1919	Varied by study centre	Age, sex, geographic region	CBT	8
Wen et al., 2002 [26]	USA and Canada	1989-1993	<15	1842	1986	Random-digit dialling	Age, sex	ALL	8
Shaw et al., 2004 [27]	Canada	1980-2000	<15	789	789	Population-based registry	Age, sex	ALL	7
Ross et al., 2005 [30]	North America	1997-2002	<20	97 (ALL), 51 (AML)	173	Roster and birth registry	Age, sex	ALL, AML	7
Schüz et al., 2007 [41]	Germany	1992-1997	0-14	650 (ALL), 105 (AML), 399 (CBT), 157 (neuroblastoma), 147 (Wilms tumour), 97 (bone tumours), 137 (soft tissue sarcoma)	2057	Population-based registry	Sex, date of birth	ALL, AML, CBT, neuroblastoma, Wilms tumour, bone tumour, soft tissue sarcoma	7
Johnson et al., 2009 [40]	USA and Canada	1993-2001	0-15	278	423	Random-digit dialling	Birth year, sex	Germ cell tumours	8
Milne et al., 2010 [28]	Australia	2003-2007	0-15	393	1249	Random-digit dialling	Age, sex, state of residence	ALL	7
Linabery et al., 2010 [31]	USA	1996-2006	<1	264 (ALL), 172 (AML)	324	State birth registry	Birth year, location of residence	ALL, AML	7
Stålberg et al., 2010 [35]	Sweden	1990-1999	0-15	512	525	Medical birth register	Location, sex, birth year	CBT	7
Ortega-García et al., 2010 [36]	Spain	2004-2006	0-15	67	155	Hospital record registry	Birth year	CBT	8
Amigou et al., 2012 [18]	France	2003-2004	0-15	764	1681	Population-based registry	Age, sex, region	ALL	7
Bailey et al., 2012 [29]	Australia	2003-2006	0-14	333	695	Random-digit dialling	Age, sex, state of residence	ALL	8
Milne et al., 2012 [37]	Australia	2005-2011	0-14	335	1363	Random-digit dialling	Age, sex, state of residence	CBT	7
Ajrouche et al., 2014 [32]	France	2010-2011	<15	636 (ALL), 100 (AML)	1421	Population-based registry, quota sampling method	Age, sex	ALL, AML	8
Amitay et al., 2016 [39]	Israel	2005-2013	1-19	121 (ALL), 69 (lymphoma)	384	Home communities	Age, sex	ALL, lymphoma	7
Singer et al., 2016 [33]	USA (California)	1995-2008	0-14	681 (ALL), 103 (AML)	1076	California birth certificates	Date of birth, sex, Hispanic ethnicity, maternal race	ALL, AML	8
Bailey et al., 2017 [38]	France	2010-2011	<15	301	1421	Population-based registry	Age, sex, region	CBT	8

NOS, Newcastle-Ottawa Scale; CBT, childhood brain tumour; ALL, acute lymphoblastic leukaemia; AML, acute myeloid leukaemia.