Characteristics of study groups
| Diagnosis | Subjects n | Males/females | Age yrs | Smoker/nonsmoker |
| Healthy controls | 20 | 12/8 | 35.1±9.6 | 11/9 |
| Lung cancer | 58 | 38/20 | 68.9±11.4 | 40/18 |
| TM | 38 | 11/27 | 67.6±14.9 | 6/32 |
| Empyema/pneumonia/septicaemia | 45 | 37/8 | 57.7±17.2 | 11/34 |
| Tuberculosis | 28 | 23/5 | 50.9±21.1 | 12/16 |
| Congestive heart failure | 45 | 19/26 | 70.7±9.5 | 22/23 |
| Total | 234 | 140/94 | 61.0±18.0 | 102/132 |
Data are presented as n and mean±sd. TM: tumours with secondaries to the lung.