title: Seasonal variation in month of birth and diagnosis in children and adolescents with Hodgkin disease and non-Hodgkin lymphoma.
abstract: OBJECTIVE
  Infections have been hypothesized to be a risk factor for Hodgkin disease and non-Hodgkin lymphoma. Because infections usually occur seasonally, the authors looked at the seasonal pattern of occurrence of these diseases, since seasonal variation in occurrence would lend support to the hypothesis of an etiologic link between infection and lymphoma.
  
  
  METHODS
  The authors identified 575 patients with Hodgkin disease and 498 with non-Hodgkin lymphoma under the age of 20 years in the Danish Cancer Registry from 1943 to 1994. A periodic regression model was used to evaluate the seasonal distribution of month of diagnosis and month of birth.
  
  
  RESULTS
  For the month of diagnosis of Hodgkin disease, the peak month of occurrence was March. The peak-to-trough ratio (the estimated incidence in the month of the peak divided by the estimated incidence in the month of the trough) was 1.57. For birth date, the ratio of case births at the peak month to case births at the trough month was 1.21, with a peak in July. There was no meaningful seasonal variation in the diagnosis or month of birth of children with non-Hodgkin lymphoma.
  
  
  CONCLUSIONS
  These data corroborate a previously reported March peak in the diagnosis of Hodgkin disease.
authors.affiliation: Department of Epidemiology and Social Medicine, University of Aarhus, Aaarhus, Denmark. vl@soci.au.dk
authors.forename: Vivian
authors.initials: V
authors.lastname: Langagergaard
authors.forename: Bente
authors.initials: B
authors.lastname: Nørgård
authors.forename: Lene
authors.initials: L
authors.lastname: Mellemkjaer
authors.forename: Lars
authors.initials: L
authors.lastname: Pedersen
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Rothman
authors.forename: Henrik Toft
authors.initials: HT
authors.lastname: Sørensen
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D003718:Denmark / Q000453:epidemiology; D006689:Hodgkin Disease / Q000453:epidemiology*; D006801:Humans; D008228:Lymphoma, Non-Hodgkin / Q000453:epidemiology*; D012042:Registries; D012621:Seasons