title: Poverty and the risk of leukemia and cancer in the central nervous system in children: A cohort study in a high-income country.
abstract: OBJECTIVE
  The association between childhood cancer and socioeconomic status is inconclusive. Family income has seldom been included in large population-based studies, and the specific contributions of it remain unknown.
  
  
  METHODS
  A total of 712,674 children born between 1967 and 2009 in the Oslo region were included. Of these, 864 were diagnosed with leukemia or cancer in the central nervous system before the age of 15 years. The association between poverty and childhood leukemia or brain cancer was analyzed using logistic regression and Cox proportional hazards models. Family income was stratified according to poverty lines. Parents' educational level and several perinatal variables were also examined.
  
  
  RESULTS
  Family poverty during the first 2 years of life was associated with lymphoid leukemia before the age of 15 years: odds ratio 1.72, 95% confidence interval 1.11-2.64. In the same age group we found a significant dose response, with a 21% increased risk of lymphoid leukemia with increasing poverty. The risk for intracranial and intraspinal embryonal tumors in the whole study period was lower for children in the middle family income category. For astrocytomas there was a more than 70% increased risk in the medium income category when analyzing the two first years of life. The observed increase was reduced when all years each child contributed to the study were included. The risk of cancer in the central nervous system overall was 20% higher in the medium income category compared to the high-income category.
  
  
  CONCLUSIONS
  Being born into a household of low family income the first 2 years of life was found to be a risk factor for development of lymphoid leukemia. For astrocytomas we observed an increased risk among children born into the medium income category throughout the first two years of life.
authors.affiliation: Agency for Health, City of Oslo, Norway ruby.kollerud@hotmail.com.
authors.forename: Ruby
authors.initials: R
authors.lastname: Del Risco Kollerud
authors.affiliation: Finance Norway, Oslo Norway.
authors.forename: Karl Gerhard
authors.initials: KG
authors.lastname: Blaasaas
authors.affiliation: Institute of Health and Society, University of Oslo, Oslo, Norway.
authors.forename: Bjørgulf
authors.initials: B
authors.lastname: Claussen
mesh_terms: D000293:Adolescent; D001254:Astrocytoma / Q000453:epidemiology; D016543:Central Nervous System Neoplasms / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004522:Educational Status; D005260:Female; D054624:Health Status Disparities; D006801:Humans; D007182:Income / Q000706:statistics & numerical data; D007223:Infant; D007231:Infant, Newborn; D007938:Leukemia / Q000453:epidemiology*; D007945:Leukemia, Lymphoid / Q000453:epidemiology; D008297:Male; D009664:Norway / Q000453:epidemiology; D011203:Poverty; D018570:Risk Assessment; D012307:Risk Factors; D012923:Social Class
keywords: CNS cancer; Leukemia; children; education; income; poverty; socioeconomic status