Table 1.

ORs and 95% CIs for colon and rectal cancer, combined and stratified, according to selected risk factors

Potential confoundersColorectal cancer
Colon cancer
Rectal cancer
OR*OR (95% CI)OR*OR (95% CI)OR*OR (95% CI)§
Family history of colorectal cancer
    No111111
    Yes1.831.89 (1.56-2.30)2.022.15 (1.73-2.68)1.381.46 (1.05-2.05)
BMI (kg/m2)
    <22111111
    ≥281.311.28 (1.04-1.56)1.371.28 (1.00-1.64)1.121.04 (0.74-1.46)
    Ptrend0.030.070.7
Colorectal cancer screening
    No111111
    Yes0.750.78 (0.67-0.90)0.780.76 (0.64-0.91)0.700.72 (0.56-0.92)
Smoking
    Never111111
    Ever1.181.20 (1.05-1.38)1.121.14 (0.96-1.34)1.391.39 (1.11-1.75)
    Ptrend (pack-years)0.040.050.4
Hormone replacement therapy
    Never users111111
    Current users0.610.66 (0.55-0.80)0.610.66 (0.53-0.82)0.600.64 (0.45-0.90)
Recreational physical activity
    None111111
    Any1.001.01 (0.87-1.17)1.041.06 (0.89-1.25)0.860.84 (0.66-1.07)
Alcohol consumption
    Never111111
    Ever0.930.93 (0.78-1.10)0.870.89 (0.74-1.08)1.071.06 (0.80-1.42)
Education
    Less than high school111111
    High school diploma0.890.92 (0.75-1.12)0.881.01 (0.80-1.29)0.920.93 (0.68-1.27)
    Some college0.920.98 (0.78-1.25)0.941.11 (0.85-1.47)0.850.88 (0.60-1.28)
    College degree or higher0.810.94 (0.71-1.25)0.841.10 (0.79-1.54)0.720.80 (0.52-1.24)
  • * Conditional on age and study of enrollment.

  • Conditional on age and study of enrollment; adjusted for family history of colorectal cancer, BMI, hormone replacement therapy use, and age at first birth.

  • Conditional on age and study of enrollment; adjusted for family history of colorectal cancer, body mass smoking, hormone replacement therapy, alcohol consumption, OC use, age at first birth, and menopausal status.

  • § Conditional on age and study of enrollment; adjusted for family history of colorectal cancer, physical activity, and hormone replacement therapy.

  • Fourth quartile versus first quartile of BMI in control women.

  • Reference categories are as follows: no history of screening proctoscopic exam (1988-1991) or (1997-2001), did not participate in recreational activity at age 20 (1988-1991) or between ages 14 and 22 (1997-2001).