Table 1.
Demographic characteristics of the study group
| N (%) | Mean (SD) | Range | |
|---|---|---|---|
| Age at joining study in years | 52.3 (13.9) | 20–81 | |
| <40 | 96 (19.1) | ||
| 40–60 | 242 (48.1) | ||
| >60 | 165 (32.8) | ||
| Height (cm) | 177.6 (6.4) | 161–201 | |
| Weight (kg) | 84.2 (12.5) | 55–145 | |
| BMI | 26.7 (3.7) | 17.2–44.8 | |
| <25 | 168 (34.8) | ||
| 25–30 | 240 (49.7) | ||
| >30 | 75 (15.5) | ||
| Serum Se level (ng/ml) | 111.6 (1.21)a | 63–305a | |
| Smoking status | |||
| Current | 27 (5.4) | ||
| Former | 148 (29.4) | ||
| Never | 328 (65.2) | ||
| Alcohol consumption | |||
| Yes | 438 (87.1) | ||
| No | 65 (12.9) | ||
| Family history of cancerb | |||
| With no family history of cancer | 165 (32.8) | ||
| With family history of cancer | 338 (67.2) | ||
| Dietary supplements | |||
| No dietary supplements taken | 275 (55.3) | ||
| Dietary supplements taken | 222 (44.7) | ||
aTo convert serum Se level in ng/ml to μmol/l multiply by 0.0127
bA positive family history of cancer was considered if one or more close relatives have recorded cancer (including grandparents, parents, siblings, children, paternal and maternal uncles and aunts)