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Table 1 Characteristics of women recruited for the TMA study and the original study*

From: Mammographic density and epithelial histopathologic markers

Variable Original study TMA study
Sample size (N) 607 159
Ethnicity (%)   
Caucasian 185 (30.5) 49 (30.8)
Hawaiian 80 (13.2) 21 (13.2)
Japanese 287 (47.3) 70 (44.0)
Other 55 (9.1) 19 (12.0)
Age at mammogram 62.1 ± 8.5 59.8 ± 8.7
Body mass index (m/kg2) 25.1 ± 5.1 24.4 ± 4.3
Family history of breast cancer (%) 104 (17.1) 17 (10.7)
Age at menarche (%)   
< 13 years 324 (54.4) 86 (54.1)
13–14 years 217 (36.4) 58 (36.5)
>14 years 55 (9.2) 15 (9.4)
Number of children (%)   
0–1 172 (28.3) 43 (27.0)
2 to 3 312 (51.4) 86 (54.1)
>3 123 (20.3) 30 (18.9)
Age at first live birth (%)   
<21 years 80 (13.6) 21 (13.2)
21–30 years 359 (61.0) 102 (64.2)
>30 years 56 (9.5) 11 (6.9)
N/A 94 (16.0) 25 (15.7)
HT use at mammogram (%)   
No use 264 (43.5) 64 (40.3)
Estrogen only 174 (28.7) 46 (28.9)
Estrogen plus progestogen 169 (27.8) 49 (30.8)
Breast measures   
   Total breast area 117.9 ± 58.1 110 ± 52.9
   Breast density in percent 35.3 ± 23.3 38.4 ± 24.8
   Absolute density 35.9 ± 27.0 39.5 ± 23.4
Menopausal Status (%)   
Premenopausal 152 (25.0) 60 (37.7)
Postmenopausal 455 (75.0) 99 (62.3)
  1. * Means ± standard deviation unless stated otherwise