title: Risk factors for synchronous primary endometrial and ovarian cancers.
abstract: OBJECTIVE
  The incidence of synchronous primary endometrial and ovarian cancer is 2- to 10-fold higher than that expected based on the incidence of each cancer alone. We sought to evaluate reasons for this in a case-control study.
  
  
  METHODS
  We combined data on a maternal history of cancer and reproductive and menstrual factors from 56 women with synchronous multiple primary disease who had participated in three population-based studies of gynecologic cancer. For comparison, we analyzed the same information from 280 women with endometrial cancer alone, 280 with ovarian cancer alone, and 280 without a history of either cancer.
  
  
  RESULTS
  The reduced risk of multiple primary disease associated with high parity (2 or more births vs 0: OR = 0.37, 95% Cl, 0.19-76) and long-term use of oral contraceptives (12 or more months vs none: OR = 0.60, 95% Cl, 0.24-1.5) tended to be more pronounced than that associated with endometrial cancer alone or with ovarian cancer alone.
  
  
  CONCLUSIONS
  Though limited by relatively small numbers, our results suggest that the presence of some common etiologies is a basis for the unusually high co-occurrence of endometrial and ovarian cancers.
authors.affiliation: Division of Research, Kaiser Permanente, Oakland, CA 94611, USA.
authors.forename: L J
authors.initials: LJ
authors.lastname: Herrinton
authors.forename: L F
authors.initials: LF
authors.lastname: Voigt
authors.forename: N S
authors.initials: NS
authors.lastname: Weiss
authors.forename: S A
authors.initials: SA
authors.lastname: Beresford
authors.forename: P A
authors.initials: PA
authors.lastname: Wingo
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D016889:Endometrial Neoplasms / Q000453:epidemiology / Q000209:etiology*; D015914:Estrogen Replacement Therapy / Q000009:adverse effects; D005260:Female; D006801:Humans; D016015:Logistic Models; D008875:Middle Aged; D009378:Neoplasms, Multiple Primary / Q000453:epidemiology / Q000209:etiology*; D016017:Odds Ratio; D010051:Ovarian Neoplasms / Q000453:epidemiology / Q000209:etiology*; D017584:Reproductive History; D012307:Risk Factors; D014861:Washington / Q000453:epidemiology