Toenail Selenium Levels and the Subsequent Risk of Prostate Cancer: A Prospective Cohort Study

Piet A. van den Brandt; Maurice P. A. Zeegers; Peter Bode; R. Alexandra Goldbohm

DOI: Published September 2003

Article Figures & Data

Tables

Table 1
Toenail selenium levels (μg/g) in prostate cancer cases according to year of follow-up, NLCS 1986–1992

Mean (±SD) selenium levels in male subcohort members were 0.547 (±0.126) μg/g (n = 1211).

Table 2

RR of prostate cancer according to toenail selenium levels, NLCS 1986–1992

Quintile of toenail Se (boundaries in μg/g)	Quintile median (μg/g)	All years of follow-up						First year excluded RR^b (95% CI)
Quintile of toenail Se (boundaries in μg/g)	Quintile median (μg/g)			Cases in cohort	Person years in subcohort	RR^a (95% CI)	RR^b (95% CI)	First year excluded RR^b (95% CI)
1 (≤0.467)	0.433	125	1444	1.00^c	1.00^c	1.00^c
2 (0.467–≤0.514)	0.494	139	1457	1.03 (0.75–1.42)	1.05 (0.74–1.47)	1.05 (0.74–1.49)
3 (0.514–≤0.560)	0.537	104	1494	0.74 (0.53–1.03)	0.69 (0.48–1.00)	0.68 (0.47–1.00)
4 (0.560–≤0.616)	0.585	83	1437	0.71 (0.50–1.01)	0.75 (0.51–1.09)	0.76 (0.51–1.11)
5 (>0.616)	0.663	89	1462	0.63 (0.45–0.90)	0.69 (0.48–0.99)	0.70 (0.48–1.01)
P for linear trend increment in standard units^d				0.001	0.008	0.012
				0.87 (0.79–0.95)	0.90 (0.81–0.99)	0.91 (0.82–1.00)

^a Adjusted for age (years, continuous).
^b 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).
^c Reference category.
^d z-scores based on In-transformed toenail selenium levels (increment of 0.190 μg/g).

Table 3

RR of prostate cancer according to toenail selenium levels and smoking status, NLCS 1986–1992

Smoking status	No. of cases	Quintile of toenail selenium (boundaries in μg/g)							P
Smoking status	No. of cases			1 (≤0.467)	2 (≤0.514)	3 (≤0.560)	4 (≤0.616)	5 (>0.616)	P
Never^a	72	1.00^b	2.28 (0.80–6.47)	0.64 (0.23–1.76)	0.33 (0.09–1.18)	1.19 (0.48–2.92)	0.412
Ex^c	300	1.00^b	0.87 (0.51–1.49)	0.53 (0.31–0.92)	0.79 (0.45–1.37)	0.46 (0.27–0.79)	0.003
Current^c	168	1.00^b	0.88 (0.51–1.52)	0.95 (0.51–1.74)	0.53 (0.25–1.14)	0.97 (0.42–2.22)	0.383

^a Adjusted for age (years), family history of prostate cancer (no/yes), level of education (low, medium, high).
^b Reference category.
^c Additionally adjusted for number of cigarettes/day, years of cigarette smoking.

Table 4

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

Group	No. of cases	Quintile of toenail selenium (boundaries in μg/g)							P
Group	No. of cases			1 (≤0.467)	2 (≤0.514)	3 (≤0.560)	4 (≤0.616)	5 (>0.616)	P
Vitamin C intake^b
Low	182	1.00^c	0.71 (0.39–1.31)	0.36 (0.18–0.71)	0.66 (0.35–1.25)	0.46 (0.24–0.89)	0.025
High	220	1.00^c	1.06 (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 intake^b
Low	204	1.00^c	1.23 (0.69–2.20)	0.55 (0.30–1.01)	0.80 (0.42–1.52)	0.70 (0.38–1.28)	0.083
High	180	1.00^c	0.80 (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 intake^b
Low	213	1.00^c	0.77 (0.43–1.37)	0.49 (0.27–0.89)	0.62 (0.35–1.13)	0.50 (0.27–0.92)	0.022
High	187	1.00^c	1.33 (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 intake^b
Low	214	1.00^c	0.69 (0.38–1.24)	0.38 (0.20–0.70)	0.51 (0.27–0.95)	0.50 (0.27–0.92)	0.019
High	185	1.00^c	1.15 (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 intake^b
Low	166	1.00^c	0.89 (0.50–1.60)	0.44 (0.23–0.83)	0.53 (0.26–1.05)	0.25 (0.12–0.54)	<0.001
High	241	1.00^c	1.25 (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 intake^b
Low	182	1.00^c	0.75 (0.40–1.39)	0.39 (0.20–0.75)	0.53 (0.28–1.02)	0.41 (0.21–0.80)	0.005
High	196	1.00^c	1.06 (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 intake^b
Low	206	1.00^c	0.76 (0.41–1.39)	0.57 (0.30–1.05)	0.64 (0.34–1.20)	0.64 (0.34–1.21)	0.146
High	202	1.00^c	1.24 (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.

Table 5

RRs for prostate cancer according to toenail selenium levels in subgroups of localized (T_0–2, M₀) and advanced (T_3–4, M₀; T_0–4, M₁) prostate tumors, NLCS 1986–1992

Quintile of toenail selenium (boundaries in μg/g)	Localized tumors (n = 189)	Advanced tumors (n = 183)
Quintile of toenail selenium (boundaries in μg/g)		RR^a (95% CI)	RR^a (95% CI)
1 (≤0.467)	1.00^b	1.00^b
2 (0.467–≤0.514)	1.29 (0.79–2.10)	0.81 (0.50–1.33)
3 (0.514–≤0.560)	0.79 (0.46–1.35)	0.59 (0.35–1.00)
4 (0.560–≤0.616)	0.74 (0.42–1.33)	0.48 (0.27–0.86)
5 (>0.616)	0.72 (0.42–1.24)	0.62 (0.37–1.05)
P for linear trend	0.043	0.020

^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 Reference category.