Parental occupation in farming and childhood cancer risk in I4C
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Transcript of Parental occupation in farming and childhood cancer risk in I4C
Parental occupation in farming and childhood cancer risk in I4C
Ann Olsson & Joachim Schüz
- Majority of case-control studies show an association- Stronger associations with indoor pesticide exposure - Internal inconsistencies, e.g. lack of dose-response - Few cohorts show no or weaker association
Rational
Case-control studies are prone to bias!
cases controls
Years between the date of birth and the date of the interview
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1
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< 4 4 -< 6 >= 6
%Recall differences regarding maternaloccupational exposureto pesticides prior to conception
Information bias
[Schüz et al., Am J Epi, 2003]
[Law, Br J Cancer, 2002]
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5
10
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30
high
med
ium lo
w
Total Responder Non-Responder
Typical pattern:Social gradientamong controls
Selection bias
I4Cfarm
• Design: Pool prospective cohorts
• Benefits:– Data collected prior to diagnosis– Data collected closer after occurrence – Increased power to study “rare events”
0 10 20 30 40 50 60 70
Africa
Asia
South America
East Europe
West Europe
North AmericaProportion of workersemployed in agriculture
Farming around the world
Global pesticide production
• Investigate if parental occupations in different types of farming is associated with increased risk of cancer in their offspring
• Evaluate the risk of childhood cancer associated with self reported parental use of pesticides during pregnancy– Compare type and frequency reported in case-control studies
• If possible assess whether the risk of childhood cancer associated with parental exposure to occupation as a farmer and pesticides vary by exposure time-windows (preconception, prenatal, and postnatal)
I4Cfarm - objectives
I4Cfarm – study team
• IARC (Ann Olsson, Joachim Schüz, Kurt Straif)• INSERM (Jacqueline Clavel)• MCRI (Gabriella Tikellis)• NCI (Martha Linet)• CREAL (Martine Vrijheid)• Eligible cohorts (PI’s)
– MoBa, DNBC, ALSPAC, THIS, ?...
Study Country Subjects Childhood cancer
Data on occupation
MoBA Norway 108 000 106 Current job – ‘Norwegian’ ISCO-88
DNBC Denmark 100 000 100-200 Current job – Danish codes
ALSPAC UK 13 000 ~30 Lifetime jobs list, details current job - UK codes
TIHS Australia 10 628 31 Current job - 4-digit Australian ISCO codes
Eligible I4C cohorts so far…
Next steps
• Eligibility of further cohorts?
• Transfer of data to MCRI (Gabriella)
• Harmonization of disease data (Martha) and occupational data (Ann & Martine)
• Data analyses (at IARC)
• Manuscripts (Study team)