Table 1.

Characteristics of colorectal cancer cases and matched controls nested in the Nurses' Health Study, 1989-2000

Cases (n = 182)Controls (n = 350)P*
Plasma C-peptide (ng/mL) geometric mean interquartile range (25-75%)1.87 (1.26-2.58)1.80 (1.15-2.72)0.42
Plasma IGFBP-1 (ng/mL) geometric mean interquartile range (25-75%)18.4 (10.2-36.3)20.0 (12.2-41.7)0.38
Plasma IGF-I (ng/mL) geometric mean interquartile range (25-75%)156.7 (123.5-206.1)147.1 (111.3-192.5)0.10
Plasma IGFBP-3 (ng/mL) geometric mean interquartile range (25-75%)4,049 (3,479-4,952)4,060 (3,489-4,952)0.42
IGF-I/IGFBP-3 molar ratio mean interquartile range (25-75%)0.15 (0.12-0.17)0.14 (0.11-0.16)0.05
Glycosylated hemoglobin (%; mean ± SD)5.34 ± 0.325.32 ± 0.350.86
Age at blood draw (mean ± SD)60.4 ± 6.560.3 ± 6.5
BMI (kg/m2; mean ± SD)24.9 ± 4.324.9 ± 4.10.52
Mean physical activity (mean MET-hours/wk ± SD)14.9 ± 15.014.5 ± 14.90.45
Alcohol (mean g/d ± SD)7.9 ± 10.96.3 ± 9.60.12
Cigarette smoking (mean pack-years ± SD)19.5 ± 25.116.3 ± 20.80.67
Current postmenopausal hormone use (%)24.732.60.06
Screening before 1990 (%)35.739.70.37
Family history of colorectal cancer (%)18.114.00.21
Multivitamin use (%)37.935.70.62
Aspirin use > 10 y (%)8.88.90.98
  • * P value for plasma biomarkers from paired t test, Wilcoxon signed rank for all other continuous variables, and χ2 test for categorical variables.