Table 1.

Characteristics of breast cancer cases and controls analyzed for CoQ10 in a nested case-control study within the SWHS, 1997 to 2006

CharacteristicsCases (n = 340)Controls (n = 653)P valuea
Age at blood draw, y; mean, SD52.4 ± 9.052.4 ± 9.00.15
Current hormone therapy use, n (%)13 (3.8)9 (1.4)0.04
Education, n (%)<0.01
Elementary and under52 (15.3)151 (23.1)
Middle school121 (35.7)267 (40.9)
High school116 (34.2)168 (25.7)
College and above50 (14.7)67 (10.3)
Body mass index, kg/m2; mean, SD
 All women24.2 ± 3.624.4 ± 3.30.29
 Premenopausal women23.4 ± 3.223.6 ± 3.10.48
 Postmenopausal women25.1 ± 3.725.3 ± 3.30.54
Physically active, n (%)122 (35.9)222 (34.0)0.67
Nulliparous, n (%)15 (4.4)24 (3.7)0.29
Number of full-term pregnancies, mean, SD1.7 ± 1.11.8 ± 1.10.05
Age at first child birth; mean, SD26.3 ± 4.125.6 ± 4.20.01
Age at menarche; mean, SD14.8 ± 1.815.0 ± 1.70.03
Months of breast feeding13.7 ± 15.616.3 ± 18.4<0.01
Smoking status, n (%)0.39
 Never335 (98.5)634 (97.1)
 Former0 (0)1 (0.1)
 Current5 (1.5)18 (2.8)
Mother or sister with breast cancer, n (%)14 (4.12)10 (1.5)0.01
Alcohol use, n (%)0.71
 Never333 (97.9)634 (97.1)
 Former1 (0.3)2 (0.3)
 Current6 (1.8)17 (2.6)
Deaths, n (%)40 (11.7)20 (3.1)<0.01
Postmenopausal, n (%)165 (48.5)320 (49.0)0.06
  • aConditional logistic regression model for categorical variables or ANOVA test for continuous variables.