Table 1. General information of case patients and control subjects.
| Variable | Cases, n (%) | Controls, n (%) | P * |
| N = 1,017 | N = 1,017 | ||
| Age (years) | |||
| Mean ± SD | 60.3±10.7 | 59.7±12.1 | 0.179 |
| ≤50 | 181(17.8) | 192(18.9) | 0.341 |
| 51∼60 | 321(31.6) | 287(28.2) | |
| 61∼70 | 324(31.9) | 351(34.5) | |
| >70 | 191(18.8) | 187(18.4) | |
| Smoking status | <0.001 | ||
| Never | 151(14.8) | 356(35.0) | |
| Former | 370(36.4) | 140(13.8) | |
| Current | 496(48.8) | 521(51.2) | |
| Pack-years smoked | <0.001 | ||
| 0 | 151(14.8) | 356(35.0) | |
| ≤26 | 215(21.1) | 326(32.1) | |
| >26 | 651(64.0) | 335(32.9) | |
| Family history of cancer | <0.001 | ||
| No | 886(87.2) | 969(95.4) | |
| Yes | 130(12.8) | 48(4.7) | |
| Histological type | |||
| Adenocarcinoma | 276(27.3) | ||
| Squamous cell carcinoma | 365(36.1) | ||
| Small cell carcinoma | 48(4.7) | ||
| Others† | 323(31.9) |
*
Two-sided chi-square test.
†
Others include large cell, bronchioalveolar, mixed cell, undifferentiated and pathologic not otherwise specified carcinomas.