Table 3

Incidence RR of bladder cancer according to toenail selenium levels and smoking status; Netherlands Cohort Study (1986–1992)

Smoking status and cessation^a	No. of cases	Quintile of toenail selenium (boundaries in μg/g)							P trend
Smoking status and cessation^a	No. of cases			1 (≤0.483)	2 (≤0.530)	3 (≤0.573)	4 (≤0.630)	5 (>0.630)	P trend
Never^b	51	1.00 (reference)	2.69 (1.02–7.09)	1.37 (0.50–3.79)	1.09 (0.38–3.14)	1.36 (0.50–3.69)	0.62
Ex^c	186	1.00 (reference)	0.74 (0.46–1.19)	0.48 (0.28–0.81)	0.49 (0.29–0.83)	0.44 (0.26–0.75)	<0.01
≤10 yrs	89	1.00 (reference)	0.42 (0.19–0.94)	0.47 (0.21–1.08)	0.45 (0.20–1.01)	0.30 (0.12–0.75)	<0.01
>10 yrs	96	1.00 (reference)	1.06 (0.55–2.06)	0.48 (0.22–1.01)	0.47 (0.20–1.09)	0.58 (0.29–1.18)	<0.01
Current^c	170	1.00 (reference)	1.36 (0.86–2.14)	0.45 (0.24–0.86)	0.76 (0.39–1.47)	1.13 (0.56–2.27)	0.25

^a P for interaction was 0.19.
^b Adjusted for age (years) and sex.
^c Adjusted for age (years), sex, number of cigarettes/day, and years of cigarette smoking.