title: Age at menarche and breast cancer risk in nulliparous women.
abstract: Early age at menarche is a known risk factor for breast cancer, some inconsistency in the literature not withstanding. Relative risks for an early menarcheal onset as compared to a late onset vary from 1.0 to 1.9. To avoid (residual) confounding by parity-related factors a case-control study was conducted among nulliparous women. 135 cases and 540 controls were selected from two population-based screening projects for breast cancer in The Netherlands. Four controls were matched to each case for year of birth, for screening-centre, and for number of screening examinations. Women with a menarcheal age of 10 or 11 years showed a 2.2 times (95% confidence interval: 1.2-4.0) higher risk for breast cancer compared to women who had their first menstrual period at 12 years of age or older.
authors.affiliation: Department of Epidemiology, Utrecht University, The Netherlands.
authors.forename: P H
authors.initials: PH
authors.lastname: Peeters
authors.forename: A L
authors.initials: AL
authors.lastname: Verbeek
authors.forename: A
authors.initials: A
authors.lastname: Krol
authors.forename: M M
authors.initials: MM
authors.lastname: Matthyssen
authors.forename: F
authors.initials: F
authors.lastname: de Waard
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001943:Breast Neoplasms / Q000209:etiology*; D016022:Case-Control Studies; D002648:Child; D005260:Female; D006801:Humans; D008572:Menarche; D008875:Middle Aged; D010298:Parity; D012044:Regression Analysis; D012307:Risk Factors