| Variables | HR (95% CI) | p-value |
| Age yrs | 1.036 (1.014–1.060) | 0.001 |
| Sex | 0.857 | |
| Female | 1 | |
| Male | 1.041 (0.673–1.611) | |
| Tumour size | 0.070 | |
| ≤3 cm | 1 | |
| >3 cm (≤7 cm) | 1.440 (0.970–2.138) | |
| Pathological stage | 0.249 | |
| IIa | 1 | |
| IIb | 1.382 (0.797–2.394) | |
| Histology type | 0.686 | |
| Squamous cell | 1 | |
| Nonsquamous cell | 1.089 (0.721–1.645) | |
| Histological grade | 0.067 | |
| Well-to-moderately differentiated | 1 | |
| Poorly differentiated | 1.589 ( 0.968–2.609) | |
| Visceral pleural invasion | 0.315 | |
| No | 1 | |
| Yes | 1.251 (0.808–1.937) | |
| Lymph nodes involved n | 0.159 | |
| Solitary | 1 | |
| Multiple | 1.325 | |
| Involved lymph node ratio | 0.044 | |
| ≤0.06 | 1 | |
| >0.06 | 1.499 (1.010–2.224) | |
| Hilar/interlobar lymph node involved | 0.013 | |
| No | 1 | |
| Yes | 1.651 (1.112–2.452) |
HR: hazard ratio.