Table 1

Selected characteristics of subjects who had complete covariate information and water source information for at least 30 of the 40 years before the interview, by case groupa

VariableControls (n = 1524)Colon cancer cases (n = 752)Rectal cancer cases (n = 647)
Continuous [mean (SD)]
Age (yr)61.0 (9.9)64.1 (8.4)63.2 (8.9)
Energy (1000 kcal/wk)10.1 (3.3)10.6 (3.6)10.6 (3.5)
Cholesterol (100 mg/wk)12.8 (5.4)13.6 (5.7)13.7 (5.6)
Calcium (500 mg/wk)11.8 (6.5)11.8 (6.6)11.8 (6.1)
Categorical (%)
Male62.956.060.7
Education
Less than complete high school38.952.955.5
Complete high school21.519.418.1
Greater than complete high school39.627.726.4
Previous medical conditions 1.4 1.7 3.4
Body mass index (kg/m2)
Low (<24)25.121.922.4
Medium (24–29)50.446.446.7
High (>29)24.531.730.9
Coffee (cups/wk)
020.123.420.3
1–2152.656.358.4
≥2227.420.421.3
Alcohol (drinks/wk)
069.265.872.0
1–725.728.122.6
≥8 5.2 6.1 5.4
  • a Subject characteristics shown are those that enter the parsimonious model for either colon or rectal cancer.