Table 2.

Relative risk of folate intake and colon cancer according to MSI status and KRAS mutation among 88,691 women from the Nurses' Health Study and 47,371 men from the Health Professionals Follow-up Study

Energy-adjusted folate intake, μg/d
Ptrend
<200200-300301-400>400
All cancer cases
    No of cases/person-years114/461,476182/757,168139/473,380231/874,861
    Age-adjusted RR (95% CI)1.00.82 (0.65-1.03)0.84 (0.66-1.08)0.76 (0.60-0.95)0.03
    Multivariate RR (95% CI)*1.00.80 (0.63-1.01)0.80 (0.61-1.04)0.75 (0.58-0.96)0.08
MSI-low/MSS cancer cases
    No of cases/Person-years89/461,496144/757,201117/473,401189/874,904
    Age-adjusted RR (95% CI)1.01.21 (0.93-1.58)0.91 (0.67-1.20)0.80 (0.62-1.03)0.05
    Multivariate RR (95% CI)*1.01.24 (0.95-1.62)0.86 (0.64-1.15)0.79 (0.60-1.03)0.11
MSI-high cancer cases
    No of cases/Person-years25/461,54938/757,29422/473,47842/875,029
    Age-adjusted RR (95% CI)1.00.77 (0.47-1.28)0.60 (0.34-1.07)0.62 (0.38-1.02)0.38
    Multivariate RR (95% CI)*1.00.75 (0.45-1.01)0.57 (0.32-1.01)0.61 (0.37-1.02)0.45
All cancer cases
    No of cases/Person-years113/461,476182/757,197142/473,402232/874,893
    Age-adjusted RR (95% CI)1.00.82 (0.65-1.04)0.87 (0.68-1.12)0.77 (0.61-0.97)0.04
    Multivariate RR (95% CI)*1.00.81 (0.63-1.02)0.82 (0.63-1.07)0.76 (0.59-0.97)0.08
KRAS-wild-type cancer cases
    No of cases/Person-years83/461,503114/757,26184/473,452146/874,968
    Age-adjusted RR (95% CI)1.01.42 (1.07-1.89)0.70 (0.52-0.96)0.66 (0.50-0.87)0.04
    Multivariate RR (95% CI)*1.01.45 (1.09-1.93)0.67 (0.49-0.92)0.66 (0.49-0.87)0.06
KRAS-mutated cancer cases
    No of cases/Person-years30/461,54368/757,29058/473,47686/875,027
    Age-adjusted RR (95% CI)1.01.16 (0.75-1.78)1.33 (0.85-2.06)1.06 (0.70-1.62)0.46
    Multivariate RR (95% CI)*1.01.13 (0.73-1.74)1.25 (0.80-1.97)1.05 (0.68-1.61)0.55
  • * Multivariate models are adjusted for age (continuous), gender, energy intake (kcal), screening sigmoidoscopy (yes/no), family history of colorectal cancer (yes/no), aspirin use (≥2 tablets/wk or less), smoking (pack-years), physical activity in METs (quintiles), body mass index in five categories (<21, 21-22.9, 23-24.9, 25-29.9, 30+), colon polyps (yes/no), beef intake (quintiles), calcium intake (quintiles), multivitamin use (yes/no), alcohol use (none, <5, 5-14.9, ≥15 g/d), and intake of vitamin B6, B12, and methionine (quintiles).

  • MSS, microsatelllite stable. KRAS mutation in codon 12 or 13.