Table 5.

Associations (multivariable HRs, 95% CIs) between continuous WCRF/AICR lifestyle and diet scoresa and colorectal cancer risk stratified by participant characteristics among men in the HPFS and women in the NHS

WCRF/AICR Lifestyle scorebWCRF/AICR Diet scorec
No. of casesMenWomenMenWomen
MenWomenHR (95% CI)PhetdHR (95% CI)PhetdHR (95% CI)PheteHR (95% CI)Phete
Age at diagnosis
 <65 years3294090.83 (0.72–0.97)0.490.99 (0.86–1.14)0.290.91 (0.77–1.07)0.411.02 (0.89–1.17)0.40
 ≥65 years8228890.75 (0.68–0.84)0.92 (0.83–1.03)0.84 (0.75–0.93)0.95 (0.87–1.05)
Aspirin/NSAID use
 Yes5406310.76 (0.66–0.86)0.310.91 (0.81–1.03)0.660.83 (0.73–0.95)0.210.96 (0.86–1.08)0.65
 No6116670.81 (0.72–0.90)0.93 (0.83–1.05)0.89 (0.79–1.00)0.97 (0.87–1.08)
Family history of colorectal cancer
 Yes2022630.74 (0.59–0.92)0.660.92 (0.75–1.11)0.960.96 (0.77–1.21)0.381.07 (0.90–1.28)0.29
 No9491,0350.79 (0.72–0.86)0.92 (0.84–1.02)0.84 (0.76–0.93)0.94 (0.86–1.02)
Smokingf
 Current701440.68 (0.45–1.03)0.320.75 (0.57–0.99)0.451.03 (0.67–1.60)0.640.68 (0.52–0.89)0.07
 Former6066560.76 (0.68–0.86)0.98 (0.86–1.11)0.84 (0.74–0.95)1.00 (0.90–1.12)
 Never4754980.82 (0.71–0.94)0.95 (0.83–1.09)0.89 (0.77–1.02)0.97 (0.86–1.10)
Multivitamin use
 Yes6227290.76 (0.67–0.86)0.500.90 (0.79–1.02)0.270.90 (0.80–1.02)0.230.92 (0.82–1.03)0.35
 No5295690.80 (0.71–0.91)0.96 (0.85–1.08)0.81 (0.71–0.92)1.00 (0.89–1.11)
BMI ≥ 25 kg/m2 in young adulthood
 Yes2541660.76 (0.63–0.91)0.650.71 (0.55–0.92)0.050.84 (0.69–1.02)0.470.84 (0.66–1.06)0.08
 No8971,1320.78 (0.71–0.86)0.96 (0.87–1.05)0.86 (0.78–0.95)0.99 (0.91–1.07)
Total calcium intake
 High5365810.88 (0.78–1.01)0.0041.03 (0.90–1.18)0.230.93 (0.82–1.06)0.071.00 (0.89–1.12)0.81
 Low6157170.71 (0.63–0.79)0.91 (0.81–1.02)0.81 (0.71–0.92)0.98 (0.88–1.09)
Diabetes
 Yes1501430.97 (0.74–1.27)0.451.08 (0.76–1.54)0.250.69 (0.51–0.92)0.151.07 (0.83–1.37)0.51
 No1,0011,1550.77 (0.71–0.85)0.98 (0.87–1.10)0.86 (0.79–0.95)0.95 (0.88–1.04)
BMI ≥ 30 kg/m2
 Obesity1532890.88 (0.67–1.16)0.380.90 (0.75–1.07)0.39
 No obesity9981,0090.87 (0.79–0.96)0.99 (0.90–1.08)
Physical activity
 High3996100.88 (0.75–1.02)0.371.04 (0.93–1.17)0.09
 Low7526880.85 (0.76–0.94)0.91 (0.82–1.02)
Oral contraceptive use
 Ever5260.94 (0.81–1.07)0.490.99 (0.87–1.12)0.57
 Never7720.93 (0.83–1.03)0.95 (0.86–1.05)
Postmenopausal hormone use
 Ever4770.93 (0.80–1.08)0.961.00 (0.87–1.14)0.72
 Never8210.92 (0.83–1.03)0.95 (0.86–1.04)
  • aPer a one-unit increase in the interquartile range for each score.

  • bAdjusted for total energy intake (kcal/day, quintiles), NSAID/aspirin use [≥2 pills/week vs. <2 pills/week (ref)], family history of colorectal cancer [yes vs. no (ref)], previous colorectal cancer screening via colonoscopy or sigmoidoscopy [yes vs. no (ref)], history of polyps [yes vs. no (ref)], smoking [never smoker (ref), >0–<10, ≥10–<20, ≥20–<30, ≥30–<40, ≥40–<50, ≥50 pack-years], multivitamin use [regular use vs. nonuse (ref)], supplemental calcium intake [none (ref), >0–<200, ≥200–<400, ≥400–<600, ≥600 mg/day], and young adult body mass index [<25 (ref), ≥25–<27.5, ≥27.5–<30, ≥30 kg/m2]; in women, additionally adjusted for menopausal status [postmenopausal vs. not (ref)] and postmenopausal hormone use [never use (ref), past use, current use].

  • cAdjusted for the same covariates as for the WCRF/AICR lifestyle score as well as physical activity (MET-hours/wk, quintiles).

  • dPinteraction between the potential effect modifier of interest and the continuous lifestyle score.

  • ePinteraction term between the potential effect modifier of interest and the continuous diet score.

  • fP values calculated by comparing a model with all two-way interactions between the exposure of interest and each category of smoking to a model without any interactions using the likelihood ratio test.