Table 1.

Characteristics of breast cancer cases and their matched controls at blood collection (1989-1990) among women in the Nurses' Health Study

CharacteristicCases (n = 701)Controls (n = 724)
Mean (SD)
Age (y)57.2 (7.0)57.1 (7.0)
Age at menarche (y)12.4 (2.0)12.5 (1.5)
BMI at age 18 (kg/m2)21.1 (2.7)21.4 (2.8)
BMI at blood collection (kg/m2)25.5 (4.8)25.3 (4.6)
Parity* (no. pregnancies >6 mo)3.2 (1.5)3.3 (1.6)
Age at first birth* (y)24.7 (4.5)24.2 (4.8)
Age at menopause (y)48.1 (8.0)47.8 (8.0)
Plasma 25(OH)D (ng/mL)31.5 (12.1)33.1 (12.7)
Plasma 1,25(OH)2D (ng/mL)33.5 (6.9)33.2 (6.1)
Percentage (%)
Postmenopausal68.367.5
Family history of breast cancer16.810.2
History of benign breast disease35.425.7
Ever smokers56.651.4
≥7 alcoholic drinks/wk14.713.3
  • * Among parous women (n = 654 cases and 656 controls).

  • Among postmenopausal women (n = 554 cases and 567 controls).

  • Sufficient plasma for assay available for 634 cases and 640 controls.