title: Risk factors for diethylstilbestrol-associated clear cell adenocarcinoma.
abstract: OBJECTIVE
  To assess the influence of postnatal factors on the development of clear cell adenocarcinoma in women exposed to diethylstilbesterol (DES), particularly factors related to exogenous or endogenous hormone exposures, and to reassess the relation of season of birth.
  
  
  METHODS
  For the analysis of postnatal factors, 244 cases were compared with 244 age-matched DES-exposed women. Information was obtained from telephone interviews, with questions asked in reference to an index age, the age at which clear cell adenocarcinoma was diagnosed. For the analysis of season of birth, 604 cases, living or deceased, were compared with 1749 DES-exposed women.
  
  
  RESULTS
  Neither oral contraceptive (OC) use nor pregnancy was associated with risk of clear cell adenocarcinoma: the odds ratios (OR) were 1.1 (95% confidence interval [CI] 0.7, 1.8) for OC use and 1.3 (95% CI 0.7, 2.3) for pregnancy. The OR for fall season of birth relative to all other seasons was 1.2 (95% CI 0.9, 1.4).
  
  
  CONCLUSIONS
  Pregnancy and OCs do not increase risk of DES-associated clear cell adenocarcinoma. In addition, season of birth does not appear to be a material factor; the previous finding of an increased risk for fall season of birth is most likely not valid and probably a chance finding due to small sample size.
authors.affiliation: Slone Epidemiology Unit, Boston University School of Medicine, Boston, Massachusetts, USA. jpalmer@slone.bu.edu
authors.forename: J R
authors.initials: JR
authors.lastname: Palmer
authors.forename: D
authors.initials: D
authors.lastname: Anderson
authors.forename: S P
authors.initials: SP
authors.lastname: Helmrich
authors.forename: A L
authors.initials: AL
authors.lastname: Herbst
mesh_terms: D018262:Adenocarcinoma, Clear Cell / Q000453:epidemiology*; D000428:Alcohol Drinking; D016022:Case-Control Studies; D015984:Causality; D003276:Contraceptives, Oral; D004054:Diethylstilbestrol / Q000009:adverse effects*; D004968:Estrogens, Non-Steroidal / Q000009:adverse effects*; D005260:Female; D006801:Humans; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D012307:Risk Factors; D014625:Vaginal Neoplasms / Q000453:epidemiology*
chemical_list: D003276:Contraceptives, Oral; D004968:Estrogens, Non-Steroidal; D004054:Diethylstilbestrol