Table 1.

Characteristics of study population

Cases (n = 1,234)Controls (n = 1,676)P value for case-control comparison*
Mean age at blood draw (y)57.157.9
Mean age at menarche (y)12.412.50.11
Mean body mass index (kg/m2)25.225.30.69
Nulliparous (%)7.56.80.45
Mean parity (among parous women)3.23.30.05
Mean age at first birth (among parous women)25.124.90.06
Premenopausal at blood draw (%)21.218.5
Benign breast disease (%)34.923.8<0.0001
Family history of breast cancer (%)16.310.6<0.0001
Median average alcohol use (g/d)2.01.80.28
FOK1 (n = 2,910)
(n = 1,234)
(n = 1,676)

FF440 (36%)661 (39%)
Ff587 (48%)777 (46%)0.05
ff207 (17%)238 (14%)
BSM1 (n = 2,728)
(n = 1,180)
(n = 1,547)

bb431 (37%)565 (37%)0.30
Bb586 (50%)737 (48%)
BB163 (14%)245 (16%)
  • * P value by t test for body mass index, alcohol, and ages at blood draw and menarche; by Wilcoxon rank-sum test for parity and age at first birth; by χ2 for all other covariates and genotype.

  • Matching factors (1:1 match for premenopausal women and 1:2 match for postmenopausal women).