Table 1 Baseline characteristics (at the time of blood collection) of eligible breast cancer cases and matched controls, Nurses’ Health Study II (1996–2011)a.
Cases | Controls | |
|---|---|---|
n = 1055 | n = 1055 | |
Age at blood collection, yearsb | 44.7 ± 4.5 | 44.8 ± 4.4 |
Race/ethnicityb | ||
Non-Hispanic White | 1021 (96.8%) | 1039 (98.5%) |
African American | 11 (1.0%) | 5 (0.5%) |
Asian- American | 17 (1.6%) | 10 (0.2%) |
Other | 6 (0.6%) | 4 (0.7%) |
Fasting at blood collectionb | 725 (68.7%) | 789 (74.8%) |
Body mass index (BMI), kg/m2 | 25.0 ± 5.2 | 25.8 ± 6.0 |
BMI at age 18, kg/m2 | 20.8 ± 2.9 | 21.1 ± 3.1 |
Weight change since age 18, kg | 11.6 ± 12.0 | 12.6 ± 13.2 |
Smoking status | ||
Never | 690 (65.4%) | 721 (68.3%) |
Past | 271 (25.7%) | 260 (24.6%) |
Current | 94 (8.9%) | 74 (7.0%) |
Physical activity, MET-hours/week | 18.1 ± 23.8 | 18.4 ± 22.7 |
AHEI diet score | 45.6 ± 10.0 | 45.7 ± 10.4 |
Alcohol intake, g/day | 4.1 ± 7.5 | 3.5 ± 6.3 |
Menopausal status and menopausal hormone therapy (MHT) useb | ||
Premenopausal | 816 (77.3%) | 810 (76.8%) |
Postmenopausal, not on MHT | 15 (1.4%) | 23 (2.2%) |
Postmenopausal, on MHT | 119 (11.3%) | 115 (10.9%) |
Unknown | 105 (10.0%) | 107 (10.1%) |
Age at menarche, years | 12.4 ± 1.3 | 12.5 ± 1.4 |
Parous | 832 (78.9%) | 887 (84.1%) |
Age at first birthc | ||
<25 years | 378 (35.8%) | 363 (34.4%) |
25–30 years | 531 (50.4%) | 543 (51.5%) |
>30 years | 146 (13.8%) | 149 (14.1%) |
Ever breastfedc | 666 (63.1%) | 685 (64.9%) |
History of benign breast disease | 234 (22.2%) | 165 (15.6%) |
Family history of breast cancer | 183 (17.3%) | 114 (10.8%) |
