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Table 1 Participant characteristics (N = 177)

From: Adolescent endogenous sex hormones and breast density in early adulthood

Characteristics N Mean (SD)
Age at blood collection during adolescence (yrs)  
 at ≤1 year visit 115 10.2 (0.6)
 at year 3 visit 167 12.1 (0.60)
 at year 5 visit 143 14.2 (0.63)
 at last visita 143 16.6 (0.88)
Age at breast MRI (yrs) 177 27.1 (1.01)
BMI at breast MRI (kg/m2) 177 25.4 (5.38)
Duration of hormonal contraceptive use (yrs) 177 5.2 (3.68)
Age at menarche (yrs) 177 12.9 (1.26)
  N Percentage
Race   
 White 162 91.5 %
 Nonwhite 15 8.5 %
Education   
 Bachelor's degree 93 52.5 %
 Graduate degree 24 33.9 %
 Other 60 13.6 %
Number of pregnancies   
 0 126 71.2 %
 ≥1 51 28.8 %
Family history of breast cancer   
 No 167 96.5 %
 Yes 6 3.5 %
Hormonal contraceptive use   
 Never 11 6.2 %
 Former 65 36.7 %
 Current 101 57.1 %
Breast density measures N Median (IQR)
 Percent dense breast volume (%) 177 24.3 (9.7-41.2)
 Absolute dense breast volume (cm3) 177 50.0 (93.3-140.3)
 Absolute nondense breast volume (cm3) 177 299.2 (157.8-484.9)
  1. Abbreviations: SD standard deviation, MRI magnetic resonance imaging, BMI body mass index, IQR interquartile range
  2. aLast visit for blood collection occurred a median of 7 years after randomization in DISC
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