Table 5.

Association of RBC folate and plasma folate levels and ERα, SFRP1, and percentage ERα/SFRP1a methylation

Mean (SE)
CountsbERαSFRP1Erα/SFRP1
RBC folate,c ng/mL
 Q1 (43.3–520.9)7110.3 (0.29)21.2 (0.52)−0.12 (0.05)
 Q2 (521.0–688.8)8010.3 (0.32)21.4 (0.54)−0.12 (0.06)
 Q3 (688.9–863.4)7311.5 (0.57)22.4 (0.69)− 0.08 (0.09)
 Q4 (863.5–1,081.1)8110.9 (0.33)22.5 (0.58)− 0.03 (0.07)
 Q5 (1,081.2–2,620.8)7711.3 (0.39)23.0 (0.56)− 0.11 (0.07)
P for trend0 0.030 0.01− 0.004
Plasma folate,c nmol/L
 Q1 (7.8–23.0)6910.8 (0.37)21.4 (0.70)−0.05 (0.08)
 Q2 (23.1–35.0)7511.4 (0.49)22.0 (0.73)− 0.05 (0.09)
 Q3 (35.1–51.4)7010.5 (0.33)22.5 (0.43)−0.01 (0.05)
 Q4 (51.5–81.4)7610.9 (0.42)22.3 (0.66)− 0.02 (0.08)
 Q5 (81.5–169.9)7910.6 (0.40)22.1 (0.60)−0.03 (0.07)
P for trend0 0.620 0.54− 0.96
  • aAverage ERα/SFRP1 is defined as (Xm)/s, where X represents the methylation data of each gene in each sample; m represents the mean of methylation of each gene among all samples; and s stands for standard deviation.

  • bN is total individuals.

  • cYear 3 RBC and plasma folate levels. The models are adjusted for age, sex, randomized folate treatment assignment, smoking status, alcohol intake, and adenoma occurrence during the 3-year randomized period.