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-upFirst year excluded RRb (95% CI)
Cases in cohortPerson years in subcohortRRa (95% CI)RRb (95% CI)
1 (≤0.467)0.43312514441.00c1.00c1.00c
2 (0.467–≤0.514)0.49413914571.03 (0.75–1.42)1.05 (0.74–1.47)1.05 (0.74–1.49)
3 (0.514–≤0.560)0.53710414940.74 (0.53–1.03)0.69 (0.48–1.00)0.68 (0.47–1.00)
4 (0.560–≤0.616)0.5858314370.71 (0.50–1.01)0.75 (0.51–1.09)0.76 (0.51–1.11)
5 (>0.616)0.6638914620.63 (0.45–0.90)0.69 (0.48–0.99)0.70 (0.48–1.01)
P for linear trend increment in standard unitsd0.0010.0080.012
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).