title: Fatherhood status and prostate cancer risk.
abstract: BACKGROUND
  Whether fatherhood status affects prostate cancer risk remains controversial. Recently, it was proposed that childless men are at lower prostate cancer risk than men with children and that men with sons may be at lower risk than men with daughters only.
  
  
  METHODS
  National population-based register data were used to address these associations between fatherhood status and prostate cancer risk. The cohort comprised all men born in Denmark between 1935 and 1988, among whom 3400 developed prostate cancer during a total of 51.6 million person-years of follow-up between 1968 and 2003.
  
  
  RESULTS
  Childless men were found to be at a 16% reduced risk of prostate cancer compared with fathers (rate ratio [RR] of 0.84; 95% confidence interval [95% CI], 0.73-0.95). The sex of the offspring did not affect prostate cancer risk (fathers with sons vs fathers without sons: RR of 0.99; 95% CI, 0.90-1.08). Among fathers, a significant trend was observed of gradually reduced prostate cancer risk with increasing number of children (P = .009), a pattern applying to both sons (P = .01) and daughters (P = .04).
  
  
  CONCLUSIONS
  Our national cohort study corroborates the view that men without children constitute a group that is at a moderately reduced risk of prostate cancer. Among men with children, there appears to be a linear decline in prostate cancer risk with increasing number of children that is independent of the sex of the offspring.
authors.affiliation: Department of Epidemiology Research at Statens Serum Institut, Copenhagen, Denmark. ktj@ssi.dk
authors.forename: Kristian T
authors.initials: KT
authors.lastname: Jørgensen
authors.forename: Bo V
authors.initials: BV
authors.lastname: Pedersen
authors.forename: Christoffer
authors.initials: C
authors.lastname: Johansen
authors.forename: Morten
authors.initials: M
authors.lastname: Frisch
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D005195:Family Relations; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009679:Nuclear Family; D011471:Prostatic Neoplasms / Q000453:epidemiology*; D012042:Registries / Q000706:statistics & numerical data; D012307:Risk Factors