title: Breast cancer in pre-menopausal women in West Africa: analysis of temporal trends and evaluation of risk factors associated with reproductive life.
abstract: BACKGROUND
  In West Africa, trends and risk factors for breast cancer (BC) have been rarely studied.
  
  
  METHODS
  Here we have analyzed trends of BC over two periods in two population-based cancer registries, in Mali-Bamako (1987-1997; 1998-2009) and in The Gambia (1988-1997; 1998-2006). We have conducted a case-control study (n = 253 cases, 249 controls) on risk factors associated with reproductive life stratified by menopausal status in Bamako.
  
  
  RESULTS
  Between the two periods, BC incidence rates increased by 20% (incidence rate ratio (IRR) 1.20 (95% CI [1.07-1.35])) in Bamako, with an annual percentage change of 2% (95% CI [0.4-3.6]). The increase was of 30% in women under 55 years (IRR 1.30 (95% CI [1.14-1.60])). A similar pattern was observed in The Gambia for women under 50 years (IRR 1.47 (95% CI [1.07-2.01])). Overall, pre-menopausal breast cancer was predominant in both countries. In contrary to what is well established, case-control study showed that late age at menarche (>14 years) increased the risk of BC among pre-menopausal women (OR: 2.02 (95% CI [1.08-3.78])) while it tended to be protective in post-menopausal women (OR: 0.61 (95% CI [0.29-1.29])). Later age at a first pregnancy (>20 years) was associated with a reduction of risk in pre-menopausal women (OR: 0.41 (95% CI [0.18-0.89])).
  
  
  CONCLUSIONS
  These results indicate that the burden of pre-menopausal BC is increasing in West African countries. These cancers appear to be associated with distinct reproductive risk factors, highlighting the need for better understanding the biological bases of early BC in African populations.
authors.affiliation: International Agency for Research on Cancer, 150 Cours Albert-Thomas, 69372 Lyon Cedex 08, France; Laboratory of Sciences Complex Decision and (in) Health Policy, University Lyon 1, Lyon, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Sighoko
authors.forename: Bakarou
authors.initials: B
authors.lastname: Kamaté
authors.forename: Cheick
authors.initials: C
authors.lastname: Traore
authors.forename: Brahima
authors.initials: B
authors.lastname: Mallé
authors.forename: Bourama
authors.initials: B
authors.lastname: Coulibaly
authors.forename: Agnès
authors.initials: A
authors.lastname: Karidiatou
authors.forename: Coulibaly
authors.initials: C
authors.lastname: Diallo
authors.forename: Ebrima
authors.initials: E
authors.lastname: Bah
authors.forename: Valerie
authors.initials: V
authors.lastname: McCormack
authors.forename: Richard
authors.initials: R
authors.lastname: Muwonge
authors.forename: Denis
authors.initials: D
authors.lastname: Bourgeois
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Gormally
authors.forename: Maria Paula
authors.initials: MP
authors.lastname: Curado
authors.forename: Siné
authors.initials: S
authors.lastname: Bayo
authors.forename: Pierre
authors.initials: P
authors.lastname: Hainaut
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000453:epidemiology*; D002277:Carcinoma / Q000453:epidemiology*; D016022:Case-Control Studies; D002648:Child; D005260:Female; D005714:Gambia / Q000453:epidemiology; D020073:Gravidity; D006801:Humans; D015994:Incidence; D008302:Mali / Q000453:epidemiology; D008572:Menarche; D008875:Middle Aged; D017698:Postmenopause; D011247:Pregnancy; D017697:Premenopause; D012042:Registries; D012307:Risk Factors; D055815:Young Adult
keywords: Africa; Breast cancer; Menopausal status; Population-based cancer registry; Risk factors; Trends