Table 4

ORsa for prostate cancer by serum selenium levelsb, stratified by age at diagnosis, time interval between examination and diagnosis, severity of disease, and cigarette smoking history

CharacteristicNo. of casesQuartile 2Quartile 3Quartile 4Two-sided P for trend
OR (95% CI)OR (95% CI)OR (95% CI)
Age at diagnosisc
≤75 years1510.8 (0.4–1.8)1.1 (0.5–2.6)0.7 (0.3–1.6)0.19
>75 years981.0 (0.5–2.2)0.8 (0.4–1.7)0.8 (0.3–1.8)0.48
Interval since examc
5–15 years1420.9 (0.5–1.8)1.0 (0.5–1.8)0.4 (0.2–0.9)0.03
>15 years880.8 (0.4–1.9)1.1 (0.5–2.7)0.7 (0.3–1.6)0.52
Severity of diseasec
Occult620.4 (0.1–1.1)0.5 (0.2–1.4)0.4 (0.1–1.2)0.19
Localized1201.1 (0.5–2.2)1.2 (0.6–2.4)0.8 (0.4–1.8)0.76
Advanced641.0 (0.4–2.8)0.9 (0.4–2.5)0.3 (0.1–0.8)0.01
Smoking historyd
Nonsmoker870.6 (0.3–1.5)1.3 (0.6–3.0)0.8 (0.4–1.9)0.93
Past smoker861.3 (0.5–3.2)0.7 (0.3–1.6)0.5 (0.2–1.1)0.03
Current smoker760.9 (0.4–2.1)0.9 (0.4–2.1)0.2 (0.1–0.8)0.02
  • a ORs and 95% confidence intervals (CIs) were estimated by the Generalized Estimating Equations approach to correct for intracluster correlation.

  • b Quartiles were based on the cutpoint value of the controls. Quartile 1 (lowest) was used as the reference group.

  • c Adjusted for cigarette smoking history (nonsmoker, past smoker, or current smoker) in addition to age (by matching).

  • d Adjusted for age because the age-matched case-control pairs were not retained in the subgroups.