title: Genetic predisposition, parity, age at first childbirth and risk for breast cancer.
abstract: BACKGROUND
  Recent studies have identified several single-nucleotide polymorphisms (SNPs) associated with the risk of breast cancer and parity and age at first childbirth are well established and important risk factors for breast cancer. The aim of the present study was to examine the interaction between these environmental factors and genetic variants on breast cancer risk.
  
  
  METHODS
  The Malmö Diet and Cancer Study (MDCS) included 17 035 female participants, from which 728 incident breast cancer cases were matched to 1448 controls. The associations between 14 SNPs and breast cancer risk were investigated in different strata of parity and age at first childbirth. A logistic regression analysis for the per allele risk, adjusted for potential confounders yielded odds ratios (OR) with 95% confidence intervals (CI).
  
  
  RESULTS
  Six of the previously identified SNPs showed a statistically significant association with breast cancer risk: rs2981582 (FGFR2), rs3803662 (TNRC9), rs12443621 (TNRC9), rs889312 (MAP3K1), rs3817198 (LSP1) and rs2107425 (H19). We could not find any statistically significant interaction between the effects of tested SNPs and parity/age at first childbirth on breast cancer risk after adjusting for multiple comparisons.
  
  
  CONCLUSIONS
  The results of this study are in agreement with previous studies of null interactions between tested SNPs and parity/age at first childbirth with regard to breast cancer risk.
authors.affiliation: Department of Surgery, Skåne University Hospital, Lund University, Malmö, Sweden. salma.butt@med.lu.se
authors.forename: Salma
authors.initials: S
authors.lastname: Butt
authors.forename: Sophia
authors.initials: S
authors.lastname: Harlid
authors.forename: Signe
authors.initials: S
authors.lastname: Borgquist
authors.forename: Malin
authors.initials: M
authors.lastname: Ivarsson
authors.forename: Göran
authors.initials: G
authors.lastname: Landberg
authors.forename: Joakim
authors.initials: J
authors.lastname: Dillner
authors.forename: Joyce
authors.initials: J
authors.lastname: Carlson
authors.forename: Jonas
authors.initials: J
authors.lastname: Manjer
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000235:genetics; D016022:Case-Control Studies; D002648:Child; D005260:Female; D059647:Gene-Environment Interaction; D020022:Genetic Predisposition to Disease; D006306:Health Surveys; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008875:Middle Aged; D016017:Odds Ratio; D010298:Parity; D020641:Polymorphism, Single Nucleotide; D011247:Pregnancy; D011446:Prospective Studies; D012042:Registries; D018570:Risk Assessment; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult