Age at menarche and breast cancer risk in nulliparous women.
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.
Peeters
P H
PH
Department of Epidemiology, Utrecht University, The Netherlands.
Verbeek
A L
AL
Krol
A
A
Matthyssen
M M
MM
de Waard
F
F
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