title: A prospective cohort study of oral contraceptive use and ovarian cancer among women in the United States born from 1947 to 1964.
abstract: OBJECTIVE
  Oral contraceptives (OCs) have been consistently associated with a reduced ovarian cancer risk; however, most previous studies included women in older birth cohorts using high-dose OC formulations. We assessed OC use, including type and dose, and ovarian cancer risk among women born between 1947 and 1964 using more recent formulations.
  
  
  METHODS
  We included 110,929 Nurses' Health Study II participants. Women reported duration of OC use and brands used from age 13 to baseline (1989) and every 2 years thereafter through 2009. We categorized brands by estrogen and progestin type, dose, and potency, and used Cox proportional hazards models, adjusted for age, calendar time, reproductive factors, and body mass index, to assess associations with ovarian cancer.
  
  
  RESULTS
  Over 2,178,679 person-years of follow-up, we confirmed 281 cases. At baseline, 83% of participants reported ever using OCs. Compared to never use, we observed an increased risk of ovarian cancer with ≤6 months of OC use (HR 1.82; 95% CI 1.13-2.93) but a non-significant 57% (95% CI 0.18-1.03) decreased risk with ≥15 years of OC use. The increased risk among short-term users (≤1 year) was restricted to OCs containing mestranol (HR 1.83; 95% CI 1.16-2.88) and first-generation progestin (HR 1.72; 95% CI 1.11-2.65).
  
  
  CONCLUSIONS
  The associations between OCs and ovarian cancer observed for this younger birth cohort differ substantially from the results of previous cohort studies, possibly reflecting changes in OC formulations and use patterns over time, although these results could be due to chance. Additional studies should evaluate newer OC formulations and ovarian cancer risk.
authors.affiliation: Division of Adolescent/Young Adult Medicine, Boston Center for Endometriosis, Boston Children's Hospital, 1 Autumn Street, 5th Floor, Boston, MA, 02115, USA. amy.shafrir@childrens.harvard.edu.|Department of Pediatrics, Harvard Medical School, Boston, MA, USA. amy.shafrir@childrens.harvard.edu.
authors.forename: Amy L
authors.initials: AL
authors.lastname: Shafrir
authors.affiliation: Division of Cancer Epidemiology, German Cancer Research Center, Heidelberg, Germany.
authors.forename: Helena
authors.initials: H
authors.lastname: Schock
authors.affiliation: Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Poole
authors.affiliation: Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA.|Obstetrics and Gynecology Epidemiology Center, Department of Obstetrics and Gynecology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Terry
authors.affiliation: Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.|Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
authors.forename: Rulla M
authors.initials: RM
authors.lastname: Tamimi
authors.affiliation: Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.|Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA.|Department of Biostatistics and Epidemiology, School of Public Health and Health Sciences, University of Massachusetts, Amherst, MA, USA.
authors.forename: Susan E
authors.initials: SE
authors.lastname: Hankinson
authors.affiliation: Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.|Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
authors.forename: Bernard A
authors.initials: BA
authors.lastname: Rosner
authors.affiliation: Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.|Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
authors.forename: Shelley S
authors.initials: SS
authors.lastname: Tworoger
mesh_terms: D000293:Adolescent; D000328:Adult; D003276:Contraceptives, Oral / Q000009:adverse effects*; D005260:Female; D006306:Health Surveys; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D010051:Ovarian Neoplasms / Q000139:chemically induced* / Q000453:epidemiology*; D011446:Prospective Studies; D014481:United States; D016387:Women's Health; D055815:Young Adult
chemical_list: D003276:Contraceptives, Oral
keywords: Ethinyl estradiol; Mestranol; Oral contraceptives; Ovarian cancer