Original Contribution Maternal Illness and Drug/Medication Use during the Period Surrounding Pregnancy and Risk of Childhood Leukemia among Offspring

Maternal illness and drug/medication use (prescription, over-the-counter, and illicit) during pregnancy might be related to childhood leukemia risk. These issues were evaluated using data (1995–2002) from the Northern California Childhood Leukemia Study. The authors selected 365 children under age 15 years who had been diagnosed with incident leukemia and birth certificate controls who were matched to them on age, sex, Hispanic ethnicity, and maternal race. Data on maternal illnesses and drug use from before pregnancy through breastfeeding were obtained by interview with the biologic mother and were analyzed by conditional logistic regression. Maternal history of influenza/pneumonia was associated with a statistically significant increased risk of acute lymphoblastic leukemia (ALL) in the offspring (odds ratio (OR) 1.89, 95 % confidence interval (CI): 1.24, 2.89), although the risk was nonsignificant for common ALL (OR 1.41, 95 % CI: 0.75, 2.63). A similar pattern of increased risk was found for history of sexually transmitted disease. Use of iron supplements was indicative of decreased ALL risk (OR 0.67, 95 % CI: 0.47, 0.94). Observing an increased risk of leukemia in children of mothers reporting a history of influenza/pneumonia and sexually transmitted disease around the time of pregnancy suggests that maternal infection might contribute to the etiology of leukemia. Furthermore, maternal iron supplement use may be protective against childhood leukemia

Original Contribution Parental Smoking and the Risk of Childhood Leukemia

Cigarette smoke has been linked to adult myeloid leukemia; however, the association between parental smoking and childhood leukemia remains unclear. Parental smoking and the risk of childhood leukemia were examined in the Northern California Childhood Leukemia Study, a case-control study, between 1995 and 2002. The present analysis included 327 acute childhood leukemia cases (281 acute lymphoblastic leukemia (ALL) and 46 acute myeloid leukemia (AML)) and 416 controls matched on age, sex, maternal race, and Hispanic ethnicity. Maternal smoking was not associated with an increased risk of either ALL or AML. Paternal preconception smoking was significantly associated with an increased risk of AML (odds ratio 3.84, 95 % confidence interval: 1.04, 14.17); an increased risk for ALL was suggestive for paternal preconception smoking (odds ratio 1.32, 95 % confidence interval: 0.86, 2.04). Greater risks of ALL were observed compared with the risk associated with paternal preconception smoking alone, when paternal preconception smoking was combined with maternal postnatal smoking (pinteraction 0.004) or postnatal passive smoking exposure (pinteraction 0.004). These results strongly suggest that exposure to paternal preconception smoking alone or in combination with postnatal passive smoking may be important in the risk of childhood leukemia. case-control studies; child; leukemia; smoking Abbreviations: ALL, acute lymphoblastic leukemia; AML, acute myeloid leukemia; CI, confidence interval; OR, odds ratio

Association of genetic variation in IKZF1, ARID5B, and CEBPE and surrogates for early-life infections with the risk of acute lymphoblastic leukemia in Hispanic children

BackgroundGenome-wide association studies focusing on European-ancestry populations have identified ALL risk loci on IKZF1, ARID5B, and CEBPE. To capture the impacts of these genes on ALL risk in the California Hispanic population, we comprehensively assessed the variation within the genes and further assessed the joint effects between the genetic variation and surrogates for early-life infections (the presence of older siblings, daycare attendance, and ear infections).MethodsGenotypic data for 323 Hispanic ALL cases and 454 controls from the California Childhood Leukemia Study were generated using Illumina OmniExpress v1 platform. Logistic regression assuming a log-additive model estimated odds ratios (OR) associated with each SNP, adjusted for age, sex, and the first five principal components. In addition, we examined potential interactions between six ALL risk alleles and surrogates for early-life infections using logistic regression models that included an interaction term.ResultsSignificant associations between genotypes at IKZF1, ARID5B, and CEBPE and ALL risk were identified: rs7780012, OR 0.50, 95% confidence interval (CI) 0.35-0.71 (p = 0.004); rs7089424, OR 2.12, 95% CI 1.70-2.65 (p = 1.16 × 10(-9)); rs4982731, OR 1.69, 95% CI 1.37-2.08 (p = 2.35 × 10(-6)), respectively. Evidence for multiplicative interactions between genetic variants and surrogates for early-life infections with ALL risk was not observed.ConclusionsConsistent with findings in non-Hispanic White population, our study showed that variants within IKZF1, ARID5B, and CEBPE were associated with increased ALL risk, and the effects for ARID5B and CEBPE were most prominent in the high-hyperdiploid ALL subtype in the California Hispanic population. Results implicate the ARID5B, CEBPE, and IKZF1 genes in the pathogenesis of childhood ALL

A task-based assessment of parental occupational exposure to pesticides and childhood acute lymphoblastic leukemia

ObjectivesAssociations between parental occupational pesticide exposure and childhood acute lymphoblastic leukemia (ALL) vary across studies, likely due to different exposure assessment methodologies.MethodsWe assessed parental occupational pesticide exposure from the year before pregnancy to the child's third year of life for 669 children diagnosed with ALL and 1021 controls. We conducted expert rating using task-based job modules (JM) to estimate exposure to pesticides among farmer workers, gardeners, agricultural packers, and pesticide applicators. We compared this method to (1) partial JM using job titles and a brief description, but without completing the task-based questionnaire, and (2) job exposure matrix (JEM) linking job titles to the International Standard Classifications of Occupation Codes. We used unconditional logistic regression to calculate odds ratios (OR) and 95% confidence intervals (95% CI) for ALL cancer risk and pesticide exposure adjusting for child's sex, age, race/ethnicity and household income.ResultsCompared to complete JMs, partial JMs and JEM led to 3.1% and 9.4% of parents with pesticide exposure misclassified, respectively. Misclassification was similar in cases and controls. Using complete JMs, we observed an increased risk of ALL for paternal occupational exposure to any pesticides (OR=1.7; 95% CI=1.2, 2.5), with higher risks reported for pesticides to treat nut crops (OR=4.5; 95% CI=0.9, 23.0), and for children diagnosed before five years of age (OR=2.3; 95% CI: 1.3, 4.1). Exposure misclassification from JEM attenuated these associations by about 57%. Maternal occupational pesticide exposure before and after birth was not associated with ALL.ConclusionsThe risk of ALL was elevated in young children with paternal occupational pesticide exposure during the perinatal period, using more detailed occupational information for exposure classification

A task-based assessment of parental occupational exposure to organic solvents and other compounds and the risk of childhood leukemia in California

PurposeData on parental occupational exposures and risk of childhood leukemia lack specificity. Using 19 task-based job modules, we examined the relationship between occupational exposure to organic solvents and other compounds and the risk of leukemia in children.MethodsLatino (48%) and non-Latino (52%) children with acute lymphoblastic leukemia (ALL; n=670), acute myeloid leukemia (AML; n=104), and controls (n=1021) were enrolled in a study in California (2000-2008). Logistic regression models were used to estimate the odds ratios (ORs) and 95% confidence intervals (CIs), adjusted for socio-demographic factors.ResultsAmong children with non-Latino fathers, none of the exposures evaluated were associated with risks of ALL and AML. In contrast, exposure to any organic solvents in Latino fathers was associated with an increased risk of childhood ALL (OR=1.48; 95% CI: 1.01-2.16); in multivariable analyses, the OR for chlorinated hydrocarbons was 2.28 (95% CI: 0.97-5.37) while the ORs were close to one for aromatic hydrocarbons, glycol ethers, and other hydrocarbon mixtures. We also observed an increased risk of ALL with exposure to combustion exhaust/polycyclic aromatic hydrocarbons (PAHs) (ORs=1.70; 95% CI: 1.16-2.57, and 1.46; 95% CI: 0.94-2.26 with and without adjustment for chlorinated hydrocarbons, respectively). Moderately elevated risks of ALL were seen with exposure to metals, paints, and wood dust, although not statistically significant. An increased risk was reported for asbestos based on small numbers of exposed Latino fathers. No associations were reported between maternal exposures to any exposures and childhood ALL and AML.ConclusionsOur data support associations between paternal occupational exposures to chlorinated hydrocarbons, combustion exhaust, metals, and possibly asbestos and the risk of ALL in the children of Latino fathers only