Table 3.

Risk of colorectal cancer associated with folate intake stratified by percent genomic leukocyte DNA methylation levels (or %5-mC), the PLCO Cancer Screening Trial, 1993–2001

%5-mC
AllFirst tertileSecond tertileThird tertile
nOR (95% CI)nOR (95% CI)nOR (95% CI)nOR (95% CI)P interaction
Natural food folate
 First tertile165/2011.0050/861.0059/601.0056/551.00
 Second tertile126/1630.87 (0.62–1.23)51/571.05 (0.58–1.91)44/521.02 (0.56–1.85)31/540.62 (0.33–1.15)
 Third tertile104/1550.81 (0.57–1.15)44/491.33 (0.72–2.47)43/550.87 (0.48–1.58)17/510.35 (0.17–0.71)
Ptrend0.230.380.640.0030.003
Fortified food folate
 First tertile143/2021.0051/781.0048/651.0044/591.00
 Second tertile154/1611.33 (0.95–1.85)56/591.82 (1.03–3.23)66/520.94 (0.50–1.76)32/501.01 (0.55–1.84)
 Third tertile98/1560.98 (0.68–1.41)38/551.02 (0.53–1.98)32/500.99 (0.51–1.90)28/511.02 (0.57–1.85)
Ptrend0.930.900.770.940.78
Total folate equivalents (food + supplements)
 First tertile164/2001.0059/781.0059/681.0046/541.00
 Second tertile118/1620.96 (0.69–1.35)43/581.01 (0.55–1.84)44/520.87 (0.49–1.56)31/520.97 (0.51–1.85)
 Third tertile113/1570.92 (0.65–1.29)43/561.02 (0.57–1.85)43/471.18 (0.65–2.16)27/540.67 (0.35–1.28)0.38
Ptrend0.620.940.650.24

NOTE: ORs and 95% CIs calculated by unconditional logistic regression adjusted for age, gender, race, time since initial sigmoidoscopy screening, year of randomization, smoking, body mass index, use of NSAIDs, a family history of colorectal cancer, and a prior history of adenoma, hyperplastic polyps, or inflammatory bowel disease or polyposis syndrome (i.e., ulcerative colitis, Crohn disease, Gardner syndrome, and familial polyposis).