Advanced paternal age and childhood cancer in offspring: A nationwide register‐based cohort study

Cancer initiation is presumed to occur in utero for many childhood cancers and it has been hypothesized that advanced paternal age may have an impact due to the increasing number of mutations in the sperm DNA with increasing paternal age. We examined the association between paternal age and specific types of childhood cancer in offspring in a large nationwide cohort of 1,904,363 children born in Denmark from 1978 through 2010. The children were identified in the Danish Medical Birth Registry and were linked to information from other national registers, including the Danish Cancer Registry. In total, 3,492 children were diagnosed with cancer before the age of 15 years. The adjusted hazard ratio of childhood cancer according to paternal age was estimated using Cox proportional hazards regressions. We found a 13% (95% confidence interval: 4–23%) higher hazard rate for every 5 years advantage in paternal age for acute lymphoblastic leukemia, while no clear association was found for acute myeloid leukemia (hazard ratio pr. 5 years = 1.02, 95% confidence interval: 0.80–1.30). The estimates for neoplasms in the central nervous system suggested a lower hazard rate with higher paternal age (hazard ratio pr. 5 years = 0.92, 95% confidence interval: 0.84–1.01). No clear associations were found for the remaining childhood cancer types. The findings suggest that paternal age is moderately associated with a higher rate of childhood acute lymphoblastic leukemia, but not acute myeloid leukemia, in offspring, while no firm conclusions could be made for other specific cancer types.     

Parental occupational exposure to pesticides,animals and organic dust and risk of childhood leukemia and central nervous system tumors: Findings from the International Childhood Cancer Cohort Consortium (I4C)

Parental occupational exposures to pesticides, animals and organic dust have been associated with an increased risk of childhood cancer based mostly on case–control studies. We prospectively evaluated parental occupational exposures and risk of childhood leukemia and central nervous system (CNS) tumors in the International Childhood Cancer Cohort Consortium. We pooled data on 329,658 participants from birth cohorts in five countries (Australia, Denmark, Israel, Norway and United Kingdom). Parental occupational exposures during pregnancy were estimated by linking International Standard Classification of Occupations-1988 job codes to the ALOHA+ job exposure matrix. Risk of childhood (<15 years) acute lymphoblastic leukemia (ALL; n = 129), acute myeloid leukemia (AML; n = 31) and CNS tumors (n = 158) was estimated using Cox proportional hazards models to generate hazard ratios (HR) and 95% confidence intervals (CI). Paternal exposures to pesticides and animals were associated with increased risk of childhood AML (herbicides HR = 3.22, 95% CI = 0.97–10.68; insecticides HR = 2.86, 95% CI = 0.99–8.23; animals HR = 3.89, 95% CI = 1.18–12.90), but not ALL or CNS tumors. Paternal exposure to organic dust was positively associated with AML (HR = 2.38 95% CI = 1.12–5.07), inversely associated with ALL (HR = 0.55, 95% CI = 0.31–0.99) and not associated with CNS tumors. Low exposure prevalence precluded evaluation of maternal pesticide and animal exposures; we observed no significant associations with organic dust exposure. This first prospective analysis of pooled birth cohorts and parental occupational exposures provides evidence for paternal agricultural exposures as childhood AML risk factors. The different risks for childhood ALL associated with maternal and paternal organic dust exposures should be investigated further.