Table 1.

Characteristics of the study participants in the nested case-control study

Case
Control
All
n (%)n (%)n (%)
No. women607 (47.7)667 (52.4)1,274 (100.0)
Ethnicity
    Hawaiian79 (13.0)162 (24.3)241 (18.9)
    Japanese292 (48.1)292 (43.8)584 (45.8)
    Caucasian195 (32.1)187 (28.0)382 (30.0)
    Other41 (6.8)26 (3.9)67 (5.3)
Born in the United States
    No51 (8.4)50 (7.5)101 (7.9)
    Yes556 (91.6)617 (92.5)1,173 (92.1)
Family history of breast cancer
    No503 (82.9)587 (88.0)1,090 (85.6)
    Yes104 (17.1)80 (12.0)184 (14.4)
Parous
    No94 (15.6)76 (11.5)170 (13.5)
    Yes508 (84.4)584 (88.5)1,092 (86.5)
Mammograms per woman
    1119 (19.6)107 (16.0)226 (17.7)
    296 (15.8)332 (49.8)428 (33.6)
    3159 (26.2)111 (16.6)270 (21.2)
    4114 (18.8)79 (11.8)193 (15.1)
    5+119 (19.6)38 (5.7)157 (12.3)

Mean (SD)
Mean (SD)
Mean (SD)
Age at recruitment (y)59.9 (8.4)57.7 (8.7)58.7 (8.6)
Age at earliest mammogram (y)57.0 (9.1)57.5 (9.5)57.3 (9.3)
Age at menarche (y)13.0 (1.5)13.1 (1.5)13.1 (1.5)
Age at first live birth (y)25.0 (4.6)24.7 (4.5)24.8 (4.5)
No. children2.3 (1.6)2.6 (1.6)2.5 (1.6)
BMI (kg/m2)24.6 (5.0)25.2 (5.4)24.9 (5.2)
No. mammograms3.2 (1.8)2.4 (1.1)2.8 (1.5)