title: Early life exposures and the risk of adult glioma.
abstract: Exposure to common infections in early life may stimulate immune development and reduce the risk for developing cancer. Birth order and family size are proxies for the timing of exposure to childhood infections with several studies showing a reduced risk of glioma associated with a higher order of birth (and presumed younger age at infection). The aim of this study was to examine whether birth order, family size, and other early life exposures are associated with the risk of glioma in adults using data collected in a large clinic-based US case-control study including 889 glioma cases and 903 community controls. A structured interviewer-administered questionnaire was used to collect information on family structure, childhood exposures and other potential risk factors. Logistic regression was used to calculate odds ratios (OR) and corresponding 95% confidence intervals (CI) for the association between early life factors and glioma risk. Persons having any siblings were at significantly lower risk for glioma when compared to those reporting no siblings (OR=0.64; 95% CI 0.44-0.93; p=0.020). Compared to first-borns, individuals with older siblings had a significantly lower risk (OR=0.75; 95% CI 0.61-0.91; p=0.004). Birth weight, having been breast fed in infancy, and season of birth were not associated with glioma risk. The current findings lend further support to a growing body of evidence that early exposure to childhood infections reduces the risk of glioma onset in children and adults.
authors.affiliation: Department of Cancer Epidemiology, H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Drive, Tampa, FL, 33612, USA.
authors.forename: Gabriella M
authors.initials: GM
authors.lastname: Anic
authors.forename: Melissa H
authors.initials: MH
authors.lastname: Madden
authors.forename: Kelly
authors.initials: K
authors.lastname: Sincich
authors.forename: Reid C
authors.initials: RC
authors.lastname: Thompson
authors.forename: L Burton
authors.initials: LB
authors.lastname: Nabors
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Olson
authors.forename: Renato V
authors.initials: RV
authors.lastname: LaRocca
authors.forename: James E
authors.initials: JE
authors.lastname: Browning
authors.forename: Edward
authors.initials: E
authors.lastname: Pan
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Egan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001722:Birth Order; D016022:Case-Control Studies; D002648:Child; D004781:Environmental Exposure / Q000009:adverse effects*; D005191:Family Characteristics; D005260:Female; D005910:Glioma / Q000453:epidemiology / Q000209:etiology*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D036801:Parturition; D012307:Risk Factors; D012621:Seasons; D035781:Siblings; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology; D055815:Young Adult