title: Oral contraceptive pills as primary prevention for ovarian cancer: a systematic review and meta-analysis.
abstract: OBJECTIVE
  To estimate the overall reduction in ovarian cancer risk associated with the use of oral contraceptive pills (OCPs) and whether reduction in risk is affected by specifics of OCP use, such as formulation or duration of use.
  
  
  METHODS
  We searched PubMed, Embase, the Cochrane Database of Systematic Reviews, and ClinicalTrials.gov for studies published from January 1990 to June 2012, with primary analysis of studies published since January 2000.
  
  
  METHODS
  We reviewed 6,476 citations. We included English-language controlled studies with human participants reporting a quantitative association between exposure to OCPs (in which the explicit or implicit indication for OCP use was prevention of pregnancy or ovarian cancer) compared with no use of OCPs. Two investigators independently reviewed the title and abstract and full-text of articles for inclusion or exclusion decision; discordant decisions were resolved by team review and consensus.
  
  
  RESULTS
  Fifty-five studies met inclusion criteria. A random-effects meta-analysis of 24 case-control and cohort studies showed significant reduction in ovarian cancer incidence in ever-users compared with never-users (odds ratio 0.73, 95% confidence interval 0.66-0.81). There was a significant duration-response relationship, with reduction in incidence of more than 50% among women using OCPs for 10 or more years. The lifetime reduction in ovarian cancer attributable to the use of OCPs is approximately 0.54% for a number-needed-to-treat of approximately 185 for a use period of 5 years.
  
  
  CONCLUSIONS
  Significant duration-dependent reductions in ovarian cancer incidence in the general population are associated with OCP use.
authors.affiliation: Departments of Obstetrics and Gynecology, Community and Family Medicine, Medicine, and Biostatistics and Bioinformatics, Duke University School of Medicine, the Duke Cancer Institute, Duke University Health System, the Duke Evidence-based Practice Center, Duke Clinical Research Institute, the Center for Health Services Research in Primary Care, Durham Veterans Affairs Medical Center, and the Duke Clinical Research Institute, Durham, North Carolina; and the Department of Obstetrics and Gynecology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina.
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Havrilesky
authors.forename: Patricia G
authors.initials: PG
authors.lastname: Moorman
authors.forename: William J
authors.initials: WJ
authors.lastname: Lowery
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Gierisch
authors.forename: Remy R
authors.initials: RR
authors.lastname: Coeytaux
authors.forename: Rachel Peragallo
authors.initials: RP
authors.lastname: Urrutia
authors.forename: Michaela
authors.initials: M
authors.lastname: Dinan
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: McBroom
authors.forename: Vic
authors.initials: V
authors.lastname: Hasselblad
authors.forename: Gillian D
authors.initials: GD
authors.lastname: Sanders
authors.forename: Evan R
authors.initials: ER
authors.lastname: Myers
mesh_terms: D003276:Contraceptives, Oral / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D010051:Ovarian Neoplasms / Q000453:epidemiology / Q000517:prevention & control*; D011247:Pregnancy; D011322:Primary Prevention / Q000379:methods*; D012306:Risk; D012308:Risk Management
chemical_list: D003276:Contraceptives, Oral