Table 1

Baseline characteristics of breast cancer cases and controls by menopausal status

Premenopausal womenPostmenopausal women
Cases (n = 69) mean (±SD)Controls (n = 265) mean (±SD)Cases (n = 64) mean (±SD)Controls (n = 238) mean (±SD)
Age (yrs)44.8 (5.0)44.4 (4.8)58.1 (5.5)57.6 (5.3)
BMI (kg/m2)24.3 (3.9)24.6 (4.6)26.0 (4.0)26.7 (4.2)
Waist-to-hip ratio0.78 (0.075)0.77 (0.06)0.81 (0.06)0.82 (0.08)
Age at menarche (yrs)12.7 (1.5)12.7 (1.5)13.2 (1.6)13.3 (1.6)
Age at menopause (yrs)49.0 (5.2)48.6 (5.2)
Age at first child (yrs)25.8 (4.5)26.0 (4.4)26.5 (5.1)26.3 (4.6)
Number of children1.8 (1.1)1.9 (1.1)1.8 (1.0)2.1 (1.6)a
Glucose (mg/dl)81.9 (18.9)78.6 (10.8)a82.2 (23.2)83.9 (34.0)
Insulin (m IU/l)9.8 (5.9)9.1 (4.4)10.5 (7.2)10.9 (7.6)
IGF-I (ng/ml)170.1 (55.2)158.8 (59.8)123.9 (44.3)130.1 (50.0)
Free IGF-I (ng/ml)1.20 (0.7)1.16 (0.8)1.26 (0.7)1.41 (0.5)
IGFBP-1 (ng/ml)31.9 (21.4)30.1 (18.3)38.9 (18.6)37.8 (21.02)
IGFBP-2 (ng/ml)415.6 (189.2)427.6 (342.9)436.2 (251.1)410.1 (193.6)
IGFBP-3 (ng/ml)3754.1 (965.1)3549.2 (753.4)a3690.0 (1025.6)3739.8 (806.0)
Employment (prevalence)
 1 low social class66.769.168.880.7
 2 middle class20.312.415.66.7
 3 high middle class13.017.015.611.3
 4 high social class0.001.50.001.3
  • a One-way ANOVA (P < 0.05): differences between cases and controls.