TABLE 1.
Distribution of study characteristics in the control subjects according to quartile (Q) of serum selenium1
| Serum selenium
|
|||||
|---|---|---|---|---|---|
| Q1 (50.5 to < 126.8) (n = 219) | Q2 (≥ 126.8 to < 141.9) (n = 220) | Q3 (≥ 141.9 to < 158.0) (n = 220) | Q4 (≥ 158.0 to 253.0) (n = 220) | P for trend | |
| Median (ng/mL) | 113.7 | 135.3 | 149.4 | 170.4 | |
| Age (y) | 64.8 ± 1.42 | 64.7 ± 1.4 | 64.7 ± 1.4 | 64.7 ± 1.4 | 0.34 |
| Prostate cancer screens (no./y)3 | 0.95 ± 0.1 | 0.97 ± 0.1 | 0.96 ± 0.1 | 0.95 ± 0.1 | 0.79 |
| Family history of prostate cancer (%) | 6.2 | 3.6 | 5.0 | 7.6 | 0.45 |
| Some college-level education (%) | 75.7 | 78.1 | 70.2 | 77.3 | 0.82 |
| BMI (kg/m2) | 27.8 ± 3.9 | 27.4 ± 3.9 | 27.2 ± 3.9 | 27.2 ± 3.9 | 0.07 |
| Vigorous physical activity ≥ 1 h/wk (%) | 67.5 | 70.5 | 68.6 | 70.9 | 0.56 |
| Aspirin use ≥ 1 times/wk (%) | 47.3 | 44.7 | 47.0 | 50.4 | 0.45 |
| Ibuprofen use ≥ 1 times/wk (%) | 16.0 | 10.8 | 12.4 | 15.9 | 0.91 |
| Smoking status (%) | |||||
| Never | 34.1 | 24.2 | 33.2 | 32.8 | 0.73 |
| Current | 8.7 | 11.2 | 7.9 | 7.7 | 0.46 |
| Former | 47.5 | 53.2 | 49.6 | 54.0 | 0.30 |
| Pipe and cigar (never cigarettes) | 9.7 | 11.4 | 9.3 | 5.6 | 0.11 |
| Alcohol use ≥ 15 g/d (%) | 33.5 | 33.6 | 30.9 | 27.9 | 0.17 |
| Energy (kcal/d) | 2380 ± 930 | 2409 ± 928 | 2385 ± 928 | 2228 ± 916 | 0.09 |
| Total fat (g/d) | 79.6 ± 17.2 | 78.4 ± 17.1 | 80.9 ± 16.9 | 78.1 ± 17.3 | 0.70 |
| Fruit (servings/d) | 3.4 ± 2.2 | 3.5 ± 2.2 | 3.5 ± 2.2 | 3.7 ± 2.2 | 0.08 |
| Vegetables (servings/d) | 5.4 ± 2.0 | 5.5 ± 2.0 | 5.3 ± 2.0 | 5.7 ± 2.0 | 0.46 |
| Red meat intake (g/d) | 103.2 ± 58.1 | 97.7 ± 58.0 | 98.1 ± 57.3 | 91.7 ± 58.5 | 0.06 |
| Dietary lycopene (μg/d) | 11 166 ± 6137 | 11 594 ± 6127 | 11 424 ± 6048 | 11 631 ± 6181 | 0.51 |
| Dietary β -carotene (μg/d) | 5041 ± 2576 | 4980 ± 2572 | 4942 ± 2539 | 5351 ± 2594 | 0.27 |
| Total vitamin E intake (IU/d) | 128 ± 242 | 141 ± 242 | 153 ± 239 | 198 ± 244 | 0.004 |
| Calcium (mg/d) | 1171 ± 452 | 1176 ± 452 | 1188 ± 446 | 1180 ± 456 | 0.79 |
1
All values other than age were standardized for age and study center. Total fat, fruit, vegetables, red meat, dietary lycopene, dietary β-carotene, total vitamin E, and calcium intakes were also standardized for energy intake.
2
x¯ ± SE (all such values).
3
Average number of prostate cancer screening examinations (prostate-specific antigen, digital rectal examination, or both) from enrollment until the year of diagnosis (cases) or until the study year in which a control was selected. Maximal period is limited to period of active screening (years 0–5).