Table 1.

Characteristics of distal colorectal adenoma cases and matched controls nested in the Nurses' Health Study, 1989-1998

Cases (n = 380)Controls (n = 380)P*
Plasma C-Peptide (ng/mL), geometric mean (25-75%)1.91 (1.19-2.80)1.71 (1.12-2.49)0.006
Plasma IGFBP-1 (ng/mL), geometric mean (25-75%)22.1 (14.4-40.1)23.9 (14.9-43.8)0.25
HbA1c (mean % ± SD)5.41 ± 0.305.38 ± 0.30.06
Age at blood draw (mean ± SD)58.2 ± 6.658.2 ± 6.50.68§
BMI (kg/m2) (mean ± SD)24.9 ± 3.724.7 ± 3.80.54
Physical activity (average 1980-1990; mean MET-h/wk ± SD)14.5 ± 18.515.7 ± 18.00.34
Alcohol (average intake 1980-1990; mean g/d ± SD)7.3 ± 10.56.8 ± 9.70.57
Cigarette smoking (mean pack-years ± SD)23.9 ± 18.021.5 ± 18.60.71
Postmenopausal hormone use in 1990 (%)32.639.50.05
Endoscopy before 1990 (%)31.633.70.32
Family history of colorectal cancer (%)24.017.60.03
Multivitamin use in 1990 (%)37.139.70.46
Regular aspirin use ≥10 y before 1990 (%)6.89.00.28
  • * P from paired t test for geometric means (plasma biomarkers), Wilcoxon signed rank for all other continuous variables, and χ2 test for categorical variables.

  • Among fasting women (cases, n = 234; controls, n = 234).

  • HbA1c available for 371 cases and 371 controls.

  • § Matching factor.

  • Among cigarette smokers.