title: Breast cancer risk after full-term pregnancies among African women from Nigeria, Cameroon, and Uganda.
abstract: BACKGROUND
  The breast cancer (BC) risk profiles of African women differ significantly from those of women of European ancestry. African women are younger at the age of onset and tend to have high parity. The purpose of this study was to examine the relationship between full-term pregnancy (FTP) and the risk of BC.
  
  
  METHODS
  A case-control study was conducted among 1995 women with invasive BC and 2631 controls in Nigeria, Cameroon, and Uganda. Odds ratios (ORs) for individual ages at FTP according to the time since delivery were calculated and adjusted for confounders. A fitted spline model was used to assess the impact of the number of pregnancies on BC risk.
  
  
  RESULTS
  In comparison with a nulliparous woman, a parous woman with her first FTP at 20 years showed an OR of 0.76 (95% confidence interval [CI], 0.57-0.99) for developing BC in the following 5 years. Ten years later, this risk was 0.76 (95% CI, 0.58-0.99) and 0.76 (95% CI, 0.58-0.98) for women aged 25 and 30 years, respectively. Similarly, a parous woman with 1 pregnancy had an OR of 0.69 (95% CI, 0.49-0.96), whereas the OR was 0.66 (95% CI, 0.48-0.91) with 2 or 5 pregnancies and 0.67 (95% CI, 0.47-0.94) with 6 pregnancies in comparison with nulliparous women.
  
  
  CONCLUSIONS
  In contrast to studies in women of European ancestry, this study showed no transient increase in the risk of developing BC after FTP among African women. Further studies are needed to examine the impact of reproductive factors on early-onset BC in African women.
authors.affiliation: Center for Clinical Cancer Genetics and Global Health, Department of Medicine, University of Chicago, Chicago, Illinois.
authors.forename: Dominique
authors.initials: D
authors.lastname: Sighoko
authors.affiliation: Department of Surgery, College of Medicine, University of Ibadan, Ibadan, Nigeria.
authors.forename: Temidayo
authors.initials: T
authors.lastname: Ogundiran
authors.affiliation: Department of Surgery, College of Medicine, University of Ibadan, Ibadan, Nigeria.
authors.forename: Adeyinka
authors.initials: A
authors.lastname: Ademola
authors.affiliation: Department of Epidemiology and Preventive Medicine, Institute of Human Virology and Greenebaum Cancer Center, University of Maryland, Baltimore, Maryland.|Institute of Human Virology, Abuja, Nigeria.
authors.forename: Clement
authors.initials: C
authors.lastname: Adebamowo
authors.affiliation: Department of Public Health Sciences, University of Chicago, Chicago, Illinois.
authors.forename: Lin
authors.initials: L
authors.lastname: Chen
authors.affiliation: Center for Population and Reproductive Health, College of Medicine, University of Ibadan, Ibadan, Nigeria.
authors.forename: Stella
authors.initials: S
authors.lastname: Odedina
authors.affiliation: Center for Population and Reproductive Health, College of Medicine, University of Ibadan, Ibadan, Nigeria.
authors.forename: Imaria
authors.initials: I
authors.lastname: Anetor
authors.affiliation: Yaounde General Hospital, Yaounde, Cameroon.
authors.forename: Paul
authors.initials: P
authors.lastname: Ndom
authors.affiliation: Mulago Hospital, Kampala, Uganda.
authors.forename: Antony
authors.initials: A
authors.lastname: Gakwaya
authors.affiliation: Center for Population and Reproductive Health, College of Medicine, University of Ibadan, Ibadan, Nigeria.
authors.forename: Oladosu
authors.initials: O
authors.lastname: Ojengbede
authors.affiliation: Department of Public Health Sciences, University of Chicago, Chicago, Illinois.
authors.forename: Dezheng
authors.initials: D
authors.lastname: Huo
authors.affiliation: Center for Clinical Cancer Genetics and Global Health, Department of Medicine, University of Chicago, Chicago, Illinois.
authors.forename: Olufunmilayo I
authors.initials: OI
authors.lastname: Olopade
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology*; D002163:Cameroon / Q000453:epidemiology; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008875:Middle Aged; D009549:Nigeria / Q000453:epidemiology; D010298:Parity; D011247:Pregnancy; D012307:Risk Factors; D014454:Uganda / Q000453:epidemiology
keywords: African; age at first full-term pregnancy; breast cancer; case-control studies; parity