Table 1

Characteristics of study participants and nodules

CharacteristicBenign (N=34)Malignant (N=20)p Value
Mean (SD) age (years)59 (5.2)61 (5.0)0.104
Current/former smoker27/714/60.652
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 years42 (17)39 (10)0.556
NoduleMean (SD) maximal diameter (mm)15 (8)13 (7)0.252
Solid/semisolid/GGO (n)20/5/915/4/10.146
Nodule size <10/≥10 mm (n)10/246/140.964
Round* (prevalence/incidence) (n)24/108/120.027
Upper lobe/lower lobes (n)21/1313/70.812
PET group I/II/III/IV (n)28/3/1/25/1/2/12<0.001
VDT group 1/2/3 (n)23/8/32/4/14<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.