title: Exposure to medical test irradiation and acute leukemia among children with Down syndrome: a report from the Children's Oncology Group.
abstract: OBJECTIVE
  The etiology of acute childhood leukemia is not well understood, particularly among children with Down syndrome, in whom a 10- to 20-fold increased risk of leukemogenesis has been reported compared with children without Down syndrome. We explored the association between medical test irradiation, a postulated leukemogenic agent, and acute leukemia among children with Down syndrome.
  
  
  METHODS
  Children with Down syndrome (controls) were frequency matched on age to children with Down syndrome and leukemia (cases) diagnosed at ages 0 to 19 years during the period 1997-2002 at participating Children's Oncology Group institutions in North America. Telephone interviews were completed with mothers of 158 cases (n = 97 acute lymphoblastic leukemia and n = 61 acute myeloid leukemia) and 173 controls. Paternal interviews were completed with 275 fathers and 40 mothers serving as surrogates. Three irradiation exposure periods were examined: preconception, in utero, and postnatal. Multivariate unconditional logistic regression models were constructed to evaluate the associations of interest, resulting in odds ratios and 95% confidence intervals.
  
  
  RESULTS
  There was little evidence that maternal or paternal preconception irradiation exposure, intrauterine exposure, or postnatal exposure contributes to leukemogenesis in children with Down syndrome. Overall, no evidence for an effect of any periconceptional exposure was observed. Similar results were observed among acute lymphoblastic leukemia and acute myeloid leukemia cases analyzed separately.
  
  
  CONCLUSIONS
  This was the first study, to our knowledge, to examine such an association among this unique patient population. The results do not provide evidence of a positive association between ionizing radiation exposure and acute leukemia among children with Down syndrome. The absence of an association should be encouraging for concerned parents of children with Down syndrome who undergo a series of diagnostic radiographs in the course of their standard care.
authors.affiliation: Division of Pediatric Epidemiology and Clinical Research, Department of Pediatrics, University of Minnesota, 420 Delaware St SE, Minneapolis, MN 55455, USA.
authors.forename: Amy M
authors.initials: AM
authors.lastname: Linabery
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Olshan
authors.forename: Alan S
authors.initials: AS
authors.lastname: Gamis
authors.forename: Franklin O
authors.initials: FO
authors.lastname: Smith
authors.forename: Nyla A
authors.initials: NA
authors.lastname: Heerema
authors.forename: Cindy K
authors.initials: CK
authors.lastname: Blair
authors.forename: Julie A
authors.initials: JA
authors.lastname: Ross
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004314:Down Syndrome / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007953:Leukemia, Radiation-Induced / Q000209:etiology*; D008297:Male; D010290:Parents