Table 4

RRa of prostate cancer according to toenail selenium levels by category of vitamin or carotenoid intake, NLCS 1986–1992

GroupNo. of casesQuintile of toenail selenium (boundaries in μg/g)P
1 (≤0.467)2 (≤0.514)3 (≤0.560)4 (≤0.616)5 (>0.616)
Vitamin C intakeb
 Low1821.00c0.71 (0.39–1.31)0.36 (0.18–0.71)0.66 (0.35–1.25)0.46 (0.24–0.89)0.025
 High2201.00c1.06 (0.62–1.82)1.28 (0.71–2.29)0.77 (0.43–1.38)0.80 (0.45–1.40)0.249
Vitamin E intakeb
 Low2041.00c1.23 (0.69–2.20)0.55 (0.30–1.01)0.80 (0.42–1.52)0.70 (0.38–1.28)0.083
 High1801.00c0.80 (0.46–1.41)0.85 (0.46–1.57)0.76 (0.40–1.44)0.61 (0.33–1.13)0.147
α-carotene intakeb
 Low2131.00c0.77 (0.43–1.37)0.49 (0.27–0.89)0.62 (0.35–1.13)0.50 (0.27–0.92)0.022
 High1871.00c1.33 (0.76–2.33)1.19 (0.64–2.19)0.93 (0.49–1.77)0.62 (0.33–1.15)0.058
β-carotene intakeb
 Low2141.00c0.69 (0.38–1.24)0.38 (0.20–0.70)0.51 (0.27–0.95)0.50 (0.27–0.92)0.019
 High1851.00c1.15 (0.67–1.96)1.13 (0.62–2.08)0.84 (0.45–1.58)0.62 (0.34–1.13)0.070
β-cryptoxanthin intakeb
 Low1661.00c0.89 (0.50–1.60)0.44 (0.23–0.83)0.53 (0.26–1.05)0.25 (0.12–0.54)<0.001
 High2411.00c1.25 (0.71–2.18)1.42 (0.79–2.54)1.12 (0.62–2.04)1.21 (0.68–2.16)0.696
Lycopene intakeb
 Low1821.00c0.75 (0.40–1.39)0.39 (0.20–0.75)0.53 (0.28–1.02)0.41 (0.21–0.80)0.005
 High1961.00c1.06 (0.62–1.80)1.05 (0.57–1.92)0.49 (0.25–0.94)0.49 (0.27–0.92)0.003
Lutein/zeaxanthin intakeb
 Low2061.00c0.76 (0.41–1.39)0.57 (0.30–1.05)0.64 (0.34–1.20)0.64 (0.34–1.21)0.146
 High2021.00c1.24 (0.72–2.13)0.89 (0.48–1.65)1.04 (0.57–1.87)0.79 (0.43–1.44)0.363
  • a Adjusted for age (years), family history of prostate cancer (no/yes), number of cigarettes/day, years of cigarette smoking, level of education (low, medium, high).

  • b Low and high are defined as the two lowest quintiles and the two highest quintiles of intake, respectively. For vitamin C, the cutoff values for low and high were: ≤82.20, >101.30 mg/day; for vitamin E the corresponding values were: ≤11.86, >15.50 mg/day, for α-carotene: ≤0.47, >0.67 mg/day, for β-carotene: ≤2.38, >2.98 mg/day, for β-cryptoxanthin: ≤0.07, >0.13 mg/day, for lycopene: ≤0.55, >0.89 mg/day and for lutein/zeaxanthin: ≤2.15, >2.60 mg/day.

  • c Reference category.