title: Combined oral contraceptive use before the first birth and epithelial ovarian cancer risk.
abstract: BACKGROUND
  Combined oral contraceptive (COC) use reduces epithelial ovarian cancer (EOC) risk. However, little is known about risk with COC use before the first full-term pregnancy (FFTP).
  
  
  METHODS
  This Canadian population-based case-control study (2001-2012) included 854 invasive cases/2139 controls aged ⩾40 years who were parous and had information on COC use. We estimated odds ratios (aORs) and 95% confidence intervals (CI) adjusted for study site, age, parity, breastfeeding, age at FFTP, familial breast/ovarian cancer, tubal ligation, and body mass.
  
  
  RESULTS
  Among parous women, per year of COC use exclusively before the FFTP was associated with a 9% risk reduction (95% CI=0.86-0.96). Results were similar for high-grade serous and endometrioid/clear cell EOC. In contrast, per year of use exclusively after the FFTP was not associated with risk (aOR=0.98, 95% CI=0.95-1.02).
  
  
  CONCLUSIONS
  Combined oral contraceptive use before the FFTP may provide a risk reduction that remains for many years, informing possible prevention strategies.
authors.affiliation: Division of Epidemiology, Biostatistics and Preventive Medicine, Department of Internal Medicine and UNM Comprehensive Cancer Center, University of New Mexico, MSC 10 5550, 1 UNM, Albuquerque, NM 87131, USA.|University of Calgary, Department of Community Health Sciences, Alberta Health Services, Calgary, Alberta, Canada.
authors.forename: Linda S
authors.initials: LS
authors.lastname: Cook
authors.affiliation: UNM Comprehensive Cancer Center, University of New Mexico, MSC 07-4025, 1 UNM, Albuquerque, NM 87131, USA.
authors.forename: Claire R
authors.initials: CR
authors.lastname: Pestak
authors.affiliation: Cancer Control Research, BC Cancer Research Centre, 675W. 10th Avenue, Vancouver, British Columbia V5Z 1L3, Canada.
authors.forename: Andy Cy
authors.initials: AC
authors.lastname: Leung
authors.affiliation: Obstetrics and Gynecology, University of Alberta, 10240 Kingsway Avenue, Edmonton, Alberta T5H 3V9, Canada.
authors.forename: Helen
authors.initials: H
authors.lastname: Steed
authors.affiliation: Department of Oncology and Obstetrics and Gynecology, Cumming School of Medicine, University of Calgary, 1331 29th Street NW, Calgary, Alberta T2N 4N2, Canada.
authors.forename: Jill
authors.initials: J
authors.lastname: Nation
authors.affiliation: Medical Oncology, BC Cancer Agency, Vancouver Centre, 600 West 10th Avenue, Vancouver, British Columbia V5Z 4E6, Canada.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Swenerton
authors.affiliation: Cancer Control Research, BC Cancer Research Centre, 675W. 10th Avenue, Vancouver, British Columbia V5Z 1L3, Canada.
authors.forename: Richard
authors.initials: R
authors.lastname: Gallagher
authors.affiliation: Department of Anatomic Pathology, H Lee Moffitt Cancer Center, 12902 USF Magnolia Drive, Tampa, FL 33612, USA.
authors.forename: Anthony
authors.initials: A
authors.lastname: Magliocco
authors.affiliation: Pathology and Laboratory Medicine, Cumming School of Medicine, University of Calgary, 2AA-07, 3280 Hospital Dr NW, Calgary, Alberta T2N 2Z6, Canada.
authors.forename: Martin
authors.initials: M
authors.lastname: Köbel
authors.affiliation: Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, 675 West 10th Ave, Vancouver, British Columbia V5Z 1L3, Canada.|Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada.
authors.forename: Angela
authors.initials: A
authors.lastname: Brooks-Wilson
authors.affiliation: Cancer Control Research, BC Cancer Research Centre, 675W. 10th Avenue, Vancouver, British Columbia V5Z 1L3, Canada.
authors.forename: Nhu
authors.initials: N
authors.lastname: Le
mesh_terms: D000328:Adult; D000368:Aged; D001722:Birth Order; D001943:Breast Neoplasms / Q000453:epidemiology; D002170:Canada / Q000453:epidemiology; D000077216:Carcinoma, Ovarian Epithelial; D016022:Case-Control Studies; D003277:Contraceptives, Oral, Combined / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009375:Neoplasms, Glandular and Epithelial / Q000453:epidemiology*; D010051:Ovarian Neoplasms / Q000453:epidemiology*; D010298:Parity; D011247:Pregnancy; D012307:Risk Factors; D013246:Sterilization, Tubal / Q000706:statistics & numerical data; D055815:Young Adult
chemical_list: D003277:Contraceptives, Oral, Combined