Table 1. Characteristics of the study population.
| Variable | Cases (n = 1,100) | Controls (n = 1,096) | P |
|---|---|---|---|
| Age (yr) | |||
| Mean ± SD | 61.4 ± 8.7 | 60.8 ± 7.4 | 0.12* |
| Gender | |||
| Male | 738 (67.1) | 736 (67.2) | 0.98† |
| Female | 362 (32.9) | 360 (32.8) | |
| Smoking status | |||
| Current | 520 (47.3) | 415 (37.9) | < 0.001† |
| Former | 267 (24.3) | 287 (26.2) | |
| Never | 313 (28.5) | 394 (35.9) | |
| Pack-years‡ | |||
| Mean ± SD | 38.7 ± 20.4 | 30.5 ± 17.4 | < 0.001* |
| Histologic type | |||
| Squamous cell carcinoma | 404 (36.7) | ||
| Adenocarcinoma | 507 (46.1) | ||
| Large cell carcinoma | 21 (1.9) | ||
| Small cell lung cancer | 148 (13.5) | ||
| NSCLC-NOS | 20 (1.8) | ||
| Stage | |||
| I | 236 (21.5) | ||
| II | 67 (6.1) | ||
| III | 361 (32.8) | ||
| IV | 436 (39.6) |
Numbers in parenthesis, column percentage. *t-test; †chi-square test; ‡in current and former smokers. SD, standard deviation; NSCLC-NOS, Non-small cell lung cancer, not otherwise specified.