Table 1

Characteristics of the study population

CharacteristicPremenopausal (n = 65)Postmenopausala (n = 192)
Age at mammogram (mean/SD)48.3/2.862.8/4.8
Percentage of breast densityb (median/range)37.1/3–8521.1/0–70
IGF-I (ng/ml; median/range)177/85–305166/54–464
IGFBP-3 (ng/ml; median/range)4000/2090–66704275/1930–8240
BMI (kg/m, mean/SD)24.9/4.125.5/4.0
History of benign breast disease (%)33%33%
Alcohol consumption (%)
None29%33%
<5 g/day38%31%
5–14.9 g/day20%20%
15+ g/day 8%10%
Nulliparous (%) 8% 9%
Age at first birth (% of parous women)
<25 yrs53%46%
30+ yrs 8%6%
Family history of breast cancer (%) 9%10%
Natural menopause (%)73%
Age at menopausec (yrs; mean/SD)49.9/3.6
Past use of postmenopausal hormones (%)38%
  • Includes only postmenopausal who were not using postmenopausal hormones at the time of blood sampling and mammography.

  • The percentage of breast density is the average of the percentage of the total areas of the left and right breasts that appear mammographically dense.

  • Age at menopause only includes women who had natural menopause or bilateral oophorectomy.