| Characteristic | Pilots (n = 83) | Comparison group (n = 50) |
| Age at blood draw in years | 46.7 (5.3), 37–55* | 45.8 (5.0), 36–56 |
| Body mass index in kg/m2 | 26.5 (2.9), 20.2–35.1 | 26.7 (3.3), 20.4–39.0 |
| Cigarette smoking | ||
| Never | 67 (80.7%)† | 43 (86.0%) |
| Ever | 16 (19.3%) | 7 (14.0%)‡ |
| Pack-years§ | 8.0 (9.7), 0.1–36 | 2.8 (3.6), 0.2–9 |
| Drink alcohol | ||
| No | 4 (4.8%) | 5 (10.0%) |
| Yes | 79 (95.2%) | 45 (90.0%) |
| Amount in g/day | 11.4 (7.4), 1.3–34.9 | 14.6 (24.3), 0.8–162.7 |
| Recreational activities past year | ||
| Vigorous activities¶ (no. of | 10.1 (3.4), 0–12 | 7.4 (5.2), 0–12 |
| months) | ||
| Family history of cancer (no. first degree relatives) | ||
| None | 39 (50.0%) | 24 (50.0%) |
| One | 35 (44.9%) | 21 (43.8%) |
| Two or more | 4 (5.1%) | 3 (6.2%) |
| Unknown | 5 | 2 |
| Cumulative red bone marrow | ||
| x ray dose score | ||
| <0.5 | 33 (39.8%) | 27 (54.0%) |
| 0.5–1.9 | 39 (47.0%) | 16 (32.0%) |
| ⩾2.0 | 11 (13.3%) | 7 (14.0%) |
*Mean (SD), range; †n (%); ‡includes one current smoker with 1.75 pack-years; §packs of cigarettes smoked/day multiplied by years of smoking; ¶vigorous activities include sports, exercise class, swimming, heavy labour or any physical exertion that involves sweating.