Previous literature
Our study aimed to address the open question whether childhood cancer is
a preventable disease by implementing interventions on candidate risk
factors . Our results are in line with those reported by recent studies
and support the hypothesis that the origins of childhood cancer seem to
be influenced not only by genetics, but also by the perturbation of the
normal developmental processes following exposure to exogenous stressors
. Currently, no primary preventive measures for childhood cancer have
been established. The main reasons include the lack of causative
determination on the level of available evidence, the lack of
determination of the effectiveness of interventions at population level,
as well as our current inability to specify the hazardous conditions in
terms of exposure level . Acknowledging the challenges in determining
causation and in quantifying the need for preventive measures to be
undertaken in the field of environmental health, we aimed to stringently
appraise the validity of evidence and potential biases in the context of
an umbrella review, namely a critical integration of evidence stemming
from currently published systematic reviews and meta-analyses. Our
grading of evidence largely conforms to systematic analyses of the
literature performed by the World Cancer Research Fund (WCRF) and the
International Agency for Research on Cancer (IARC), as well as to the
protocols proposed by the US Preventive Services Task Force (USPSTF) .
A strong level of evidence was not supported by the present study
primarily due to the presence of biases (i.e. significant between-study
heterogeneity). However, beyond these limitations, our results provided
highly suggestive evidence for some specific and potentially preventable
risk factors of childhood cancer, which supports those reported by
recently published studies, systematic reviews and pooled analyses from
large consortia .