title: Hormonal factors and the risk of invasive ovarian cancer: a population-based case-control study.
abstract: OBJECTIVE
  To examine the influence of hormone-related factors on the risk of invasive epithelial ovarian cancer (ovarian cancer).
  
  
  METHODS
  Population-based case-control study using in-person interviews.
  
  
  METHODS
  Academic department of preventive medicine.
  
  
  METHODS
  Four hundred seventy-seven ovarian cancer patients and 660 controls.
  
  
  METHODS
  None.
  
  
  METHODS
  Numbers of and ages at births, oral contraceptive use, and use of menopausal hormone therapy.
  
  
  RESULTS
  Compared with nulliparous women, women whose only (last) birth was after age 35 years had an estimated 51% (95% confidence interval: 21%-70%) reduction in risk. If this birth occurred earlier, the reduction in risk was progressively less. Additional (earlier) births reduced the risk further. Oral contraceptive use also reduced risk. Increased body mass index increased risk, but this effect was confined to localized disease and is likely to be a diagnostic bias, as a consequence of other problems associated with being overweight and in itself having no etiological significance.
  
  
  CONCLUSIONS
  If the major protective effect of a late birth can be confirmed, our most challenging task will be to understand the mechanism to develop a chemoprevention approach to exploit this finding.
authors.affiliation: USC/Norris Comprehensive Cancer Center, Keck School of Medicine, Department of Preventive Medicine, University of Southern California, Los Angeles, California 90033, USA. mcpike@usc.edu
authors.forename: Malcolm C
authors.initials: MC
authors.lastname: Pike
authors.forename: Celeste L
authors.initials: CL
authors.lastname: Pearce
authors.forename: Ruth
authors.initials: R
authors.lastname: Peters
authors.forename: Wendy
authors.initials: W
authors.lastname: Cozen
authors.forename: Peggy
authors.initials: P
authors.lastname: Wan
authors.forename: Anna H
authors.initials: AH
authors.lastname: Wu
mesh_terms: D000328:Adult; D015992:Body Mass Index; D016022:Case-Control Studies; D003276:Contraceptives, Oral / Q000494:pharmacology; D005260:Female; D006728:Hormones / Q000097:blood*; D006801:Humans; D008423:Maternal Age; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D010051:Ovarian Neoplasms / Q000209:etiology* / Q000473:pathology / Q000517:prevention & control*; D018566:Pregnancy, High-Risk; D018570:Risk Assessment; D011795:Surveys and Questionnaires
chemical_list: D003276:Contraceptives, Oral; D006728:Hormones