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Table 1 Selected characteristics of study subjects by ethnicity: premenopausal women

From: Cytochrome P450 1A2 (CYP1A2) activity and risk factors for breast cancer: a cross-sectional study

  With CYP1A2 results No CYP1A2 results5 (n = 36)
  Caucasian1 (n = 125) East Asian2 (n = 4) Jewish3 (n = 10) Other4 (n = 7)  
Risk factors      
   Age (years) 44.8 (4.8) 46.8 (4.5) 45.4 (3.1) 44.7 (5.1) 45.1 (4.4)
   Weight (kg) 68.1 (16.6) 54.8 (3.1) 59.4 (10.7) 64.9 (17.9) 69.1 (13.3)
   BMI (kg/m2) 25.3 (6.1) 23.2 (0.9) 22.6 (3.5) 25.9 (6.5) 25.8 (5.1)
   WHR 0.75 (0.06) 0.75 (0.04) 0.73 (0.07) 0.77 (0.05) 0.74 (0.06)
   Age at menarche (years) 12.8 (1.5) 11.5 (1.3) 12.2 (0.6) 13.7 (1.6) 12.6 (1.5)
   Age at first birth (years) 27.8 (5.7) 29.5 (0.7) 29.5 (2.7) 25.6 (9.7) 29.0 (6.4)
   Number of live births 1.4 (1.2) 1.0 (1.2) 2.1 (1.3) 1.6 (1.3) 1.5 (1.2)
   Mammographic density (%)6 27.4 (23.2) 47.6 (17.0) 40.2 (22.7) 25.9 (20.0) 28.4 (20.5)
   CYP1A2 activity (CMR)7 6.3 (3.0) 6.5 (1.0) 5.0 (1.0) 6.1 (3.5) -
Hormones      
   Estradiol (pmol/l) 326.2 (217.0) 188.0 (127.6) 241.6 (173.3) 337.9 (188.4) 295.9 (221.5)
   Free estradiol (%) 2.1 (0.7) 1.7 (0.5) 1.8 (0.7) 2.3 (0.7) 2.3 (0.5)
   SHBG (nmol/l) 57.3 (27.1) 70.8 (17.2) 69.1 (26.6) 48.4 (24.6) 48.3 (19.0)
   IGF-1 (ng/ml) 158.5 (35.6) 154.5 (36.2) 139.7 (36.6) 144.4 (24.8) 143.4 (34.0)
   IGFBP-3 (mg/l) 2.7 (0.5) 2.6 (0.4) 2.7 (0.6) 2.7 (0.4) 2.6 (0.5)
   Insulin (pmol/l) 74.0 (43.6) 47.4 (20.2) 53.8 (33.6) 86.0 (40.8) 77.0 (36.8)
Nutritional variables      
   Caffeine intake (mg/day) 161.0 (100.8) 138.8 (90.9) 132.0 (109.1) 212.9 (148.6) 58.0 (58.8)
   Total energy intake (kcal/day) 1707.9 (467.1) 1640.0 (624.9) 1568.2 (346.4) 1995.4 (877.1) 1749.3 (485.2)
Blood lipids      
Total cholesterol (mmol/l) 4.7 (0.9) 4.8 (0.4) 4.8 (0.8) 5.1 (0.9) 5.0 (1.0)
Triglycerides (mmol/l) 1.3 (0.9) 1.1 (0.1) 1.1 (0.5) 1.0 (0.6) 1.5 (1.1)
  1. Values are expressed as mean (standard deviation). 1 n = 86 for age at first birth; n = 124 for free estradiol, insulin-like growth factor (IGF-1), and IGF binding protein (IGFBP)-3; n = 121 for caffeine intake; and n = 123 for total energy intake. 2 n = 2 for age at first birth. 3 n = 8 for age at first birth. 4 n = 5 for age at first birth. 5 n = 25 for age at first birth and n = 7 for caffeine. 6Proportion of breast area occupied by dense tissue. 7Estimated by caffeine metabolic ratio (CMR; see text for details). BMI, body mass index; WHR, waist–hip ratio.
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