title: Mode of delivery and risk of childhood leukemia.
abstract: BACKGROUND
  Childhood infection and immune response have long been suspected in the etiology of childhood leukemia, specifically acute lymphoblastic leukemia (ALL). Normal primary inoculation of the core human microbiome is circumvented by cesarean section (CS) delivery, which is a proposed modulator of both immune response and early-life infection.
  
  
  METHODS
  In this study, we examined CS delivery and the risk of childhood leukemia using data from the California Childhood Leukemia Study (CCLS) case-control study and additive logistic regression models.
  
  
  RESULTS
  We observed no association between CS and acute myelogenous leukemia [OR, 0.96; 95% confidence interval (CI), 0.52-1.55]. We observed a suggestive association for ALL and CS (OR, 1.22; 95% CI, 0.97-1.54). When examining common ALL (cALL), defined as ALL with expression of CD10 and CD19 surface antigens and diagnosis occurring between 2 and 5.9 years of age, we found a significant association with CS (OR, 1.44; 95% CI, 1.0-2.06). ALL subjects that are not cALL showed a similar risk as ALL overall (OR, 1.15; 95% CI, 0.91-1.44). Because of previous findings suggesting effect modification, we stratified cALL subjects by Hispanic status. Although we observed no relationship for CS in non-Hispanics (OR, 1.14; 95% CI, 0.72-1.79), we did observe a strong association between cALL and CS in Hispanics (OR, 2.34; 95% CI, 1.23-4.46).
  
  
  CONCLUSIONS
  Within the CCLS, CS delivery seems to be associated with cALL and Hispanic subjects may be driving the association.
  
  
  CONCLUSIONS
  Further research combined with investigations into response to early infection and the microbiome is warranted.
authors.affiliation: Authors' Affiliations: Departments of Epidemiology; and Biostatistics, University of California, Berkeley; Department of Epidemiology and Biostatistics, University of California, San Francisco; Department of Pediatric Oncology, Children's Hospital Central California, Madera; and Division of Pediatric Hematology/Oncology, UCLA David Geffen School of Medicine, Los Angeles, California.
authors.forename: Stephen Starko
authors.initials: SS
authors.lastname: Francis
authors.forename: Steve
authors.initials: S
authors.lastname: Selvin
authors.forename: Catherine
authors.initials: C
authors.lastname: Metayer
authors.forename: Amelia D
authors.initials: AD
authors.lastname: Wallace
authors.forename: Vonda
authors.initials: V
authors.lastname: Crouse
authors.forename: Theodore B
authors.initials: TB
authors.lastname: Moore
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Wiemels
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Buffler
mesh_terms: D002140:California; D016022:Case-Control Studies; D002585:Cesarean Section / Q000009:adverse effects*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006630:Hispanic or Latino / Q000706:statistics & numerical data; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000208:ethnology / Q000209:etiology*; D008297:Male; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000208:ethnology / Q000209:etiology*; D011379:Prognosis; D012307:Risk Factors; D044465:White People / Q000706:statistics & numerical data