Table 4

Incidence RRa of bladder cancer according to toenail selenium levels by category of vitamin intake; Netherlands Cohort Study (1986–1992)

GroupNo. of casesQuintile of toenail selenium (boundaries in μg/g)P-trend
1 (≤0.483)2 (≤0.530)3 (≤0.573)4 (0.630)5 (>0.630)
β-Carotene intakeb
 Low1671.00 (reference)0.98 (0.59–1.62)0.50 (0.28–0.89)0.71 (0.40–1.26)0.65 (0.36–1.16)0.02
 High1551.00 (reference)1.08 (0.65–1.80)0.97 (0.55–1.71)0.66 (0.34–1.26)0.74 (0.41–1.34)0.09
Vitamin C intakeb
 Low1811.00 (reference)0.95 (0.59–1.53)0.45 (0.26–0.78)0.72 (0.41–1.26)0.77 (0.43–1.37)0.05
 High1401.00 (reference)1.09 (0.64–1.85)1.01 (0.57–1.80)0.50 (0.25–1.00)0.75 (0.41–1.37)0.06
Vitamin E intakeb
 Low1451.00 (reference)1.37 (0.81–2.33)0.58 (0.30–1.09)0.76 (0.41–1.42)0.82 (0.45–1.50)0.07
 High1701.00 (reference)1.09 (0.68–1.75)0.59 (0.34–1.03)0.70 (0.38–1.28)0.73 (0.41–1.29)0.04
  • a Adjusted for age (years), sex, number of cigarettes/day, and years of cigarette smoking.

  • b Low and high are defined as the two lowest quintiles and the two highest quintiles of intake, respectively. For β-carotene, the cutoff values for low and high were: ≤2.36, >2.97 mg/day; for vitamin C the corresponding values were ≤86.60 and >107.71 mg/day, and for vitamin E the corresponding values were ≤10.72 and <13.89 mg/day. The Ps for interaction were 0.58, 0.16, and 0.96 for β-carotene, vitamin C, and vitamin E.