Characteristics of study participants and nodules
| Characteristic | Benign (N=34) | Malignant (N=20) | p Value | |
| Participants† | Women/men | 18/16 | 9/11 | 0.778 |
| Mean (SD) age (years) | 59 (5.2) | 61 (5.0) | 0.104 | |
| Current/former smoker | 27/7 | 14/6 | 0.652 | |
| Mean (SD) FEV1 (l) | 2.5 (0.6) | 2.3 (0.6) | 0.147 | |
| Mean (SD) FEV1 (% predicted) | 85 (18) | 77 (18) | 0.109 | |
| Mean (SD) pack years | 42 (17) | 39 (10) | 0.556 | |
| Nodule | Mean (SD) maximal diameter (mm) | 15 (8) | 13 (7) | 0.252 |
| Solid/semisolid/GGO (n) | 20/5/9 | 15/4/1 | 0.146 | |
| Nodule size <10/≥10 mm (n) | 10/24 | 6/14 | 0.964 | |
| Round* (prevalence/incidence) (n) | 24/10 | 8/12 | 0.027 | |
| Upper lobe/lower lobes (n) | 21/13 | 13/7 | 0.812 | |
| PET group I/II/III/IV (n) | 28/3/1/2 | 5/1/2/12 | <0.001 | |
| VDT group 1/2/3 (n) | 23/8/3 | 2/4/14 | <0.001 | |
↵* Round indicates the screening round in which the nodule was first observed.
↵† One man participated twice in the study. He had two nodules, one at baseline (benign) and the other at the incidence round (malignant).
PET and VDT groups I and 1 indicate benignity (the higher the number, the greater the likelihood of malignancy).
FEV1, forced expiratory volume in 1 s; GGO, ground glass opacity; PET, positron emission tomography; VDT, volume doubling time.