Table 1.

Characteristics of women at the time of entry into the study

n%
Age
    <403,7646.1
    40–4411,68918.9
    45–4910,97617.7
    50–549,64215.6
    55–596,84611.1
    60–645,5689.0
    65–695,0758.2
    70–744,1616.7
    ≥754,1346.7
Family history of breast cancer
    No50,22881.2
    Yes11,61618.8
Age at first childbirth
    <2115,29524.8
    21–3031,39651.0
    >305,6689.2
    No children9,21915.0
Menopausal status
    Premenopausal24,23839.2
    Postmenopausal37,60660.8
Postmenopausal hormone therapy
    Currently using13,34540.2
    Formerly used3,38510.2
    Never used16,47149.6
BMI (kg/m2)
    <22.013,36322.0
    22.0–24.915,83726.1
    25.0–27.410,54117.3
    27.5–29.97,59512.5
    ≥3013,44922.1
Breast density
    Entirely fat4,4097.1
    Scattered33,39754.0
    Heterogeneous19,01530.7
    Extremely5,0238.1