title: Residential mobility and the risk of childhood leukemia.
abstract: OBJECTIVE
  An infective origin of childhood leukemia has been postulated, with leukemia developing as a rare response to an infection. Population mixing can result in increased contacts between infected and susceptible individuals and may increase the risk of leukemia. The objective of this study was to investigate the association between residential mobility as an indicator of population mixing at individual level and the risk of leukemia in children (<15 years).
  
  
  METHODS
  We conducted a population-based case-control study using Finnish register data. Cases (n = 1,093) were all children diagnosed with leukemia (M9800-M9948 in ICD-O-3) at <15 years of age in Finland in 1990-2011. We chose randomly three controls per case (n = 3,279), free of cancer and alive in the end of the index year (diagnosis of the case). Controls were matched by sex and age. A comprehensive history of residential mobility was constructed from the population registry including overall migration, moving to a larger municipality (more inhabitants), and moving to a municipality with low, intermediate, or high migration intensity. The association between residential mobility and the risk of childhood leukemia was evaluated using conditional logistic regression.
  
  
  RESULTS
  We did not observe consistently increased or decreased risks of childhood leukemia associated with different migration patterns. Overall, residential mobility showed odds ratios nonsignificantly below unity, and no elevated risks were found.
  
  
  CONCLUSIONS
  Our results do not indicate that higher residential mobility or moving to municipalities with more inhabitants is associated with risk of childhood leukemia.
authors.affiliation: School of Health Sciences, University of Tampere, 33014, Tampere, Finland.
authors.forename: Laura
authors.initials: L
authors.lastname: Järvelä
authors.affiliation: School of Health Sciences, University of Tampere, 33014, Tampere, Finland.|UKK Institute for Health Promotion, Tampere, Finland.
authors.forename: Jani
authors.initials: J
authors.lastname: Raitanen
authors.affiliation: Tampere Center for Child Health Research, University of Tampere Medical School and Tampere University Hospital, Tampere, Finland.
authors.forename: Sini
authors.initials: S
authors.lastname: Erme
authors.affiliation: Tampere Center for Child Health Research, University of Tampere Medical School and Tampere University Hospital, Tampere, Finland.
authors.forename: Olli
authors.initials: O
authors.lastname: Lohi
authors.affiliation: School of Health Sciences, University of Tampere, 33014, Tampere, Finland. anssi.auvinen@uta.fi.|STUK - Radiation and Nuclear Safety Authority, Helsinki, Finland. anssi.auvinen@uta.fi.|Tampere Center for Child Health Research, University of Tampere Medical School and Tampere University Hospital, Tampere, Finland. anssi.auvinen@uta.fi.
authors.forename: Anssi
authors.initials: A
authors.lastname: Auvinen
mesh_terms: D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004781:Environmental Exposure; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D007223:Infant; D007938:Leukemia / Q000453:epidemiology*; D016015:Logistic Models; D008297:Male; D016017:Odds Ratio; D011157:Population Dynamics; D012042:Registries
keywords: Case–control studies; Human migration; Infection; Leukemia; Population dynamics