Patient characteristics
| Characteristic | Discovery (n=536) | Validation (n=405) | P value |
| Mean age (SD), years | 65.4 (10.4) | 67.0 (9.4) | 0.02 |
| Gender | 0.36 | ||
| Male | 246 (45.9) | 198 (48.9) | |
| Female | 290 (54.1) | 207 (51.1) | |
| Mean no of smoking pack years, (SD) | 54.2 (34.1) | 53.3 (33.6) | 0.72 |
| Smoking status | 3.89E-12 | ||
| Never | 108 (20.1) | 17 (4.2) | |
| Former | 243 (45.3) | 237 (58.5) | |
| Current | 185 (34.5) | 151 (37.3) | |
| Tumor stage* | 0.6 | ||
| I | 358 (66.8) | 277 (68.4) | |
| II | 178 (33.2) | 128 (31.6) | |
| Tumor grade | 0.13 | ||
| Well differentiated | 54 (10.1) | 45 (11.1) | |
| Moderately differentiated | 202 (37.7) | 133 (32.8) | |
| Poorly differentiated | 195 (36.4) | 160 (39.5) | |
| Undifferentiated | 13 (2.4) | 3 (0.7) | |
| Unknown | 72 (13.4) | 64 (15.8) | |
| ECOG score | 2.60E-07 | ||
| 0 | 106 (19.8) | 100 (24.7) | |
| 1 | 127 (23.7) | 146 (36.0) | |
| 2 | 25 (4.7) | 24 (5.9) | |
| No record | 278 (51.9) | 135 (33.3) | |
| Histology | |||
| Adenocarcinoma | 314 (58.6) | 228 (56.3) | 0.08 |
| Squamous cell carcinoma | 137 (25.6) | 127 (31.4) | |
| Other‡ | 85 (15.9) | 50 (12.4) | |
| Treatment | 4.00E-04 | ||
| No surgery† | 74 (13.8) | 94 (23.2) | |
| Surgery only | 311 (58.0) | 208 (51.4) | |
| Surgery plus chemotherapy | 132 (24.6) | 98 (24.2) | |
| Surgery plus radiation | 19 (3.6) | 5 (1.2) | |
| Recurrence | 0.4 | ||
| No | 339 (63.2) | 267 (65.9) | |
| Yes | 197 (36.8) | 138 (34.1) | |
| Vital status | 1.30E-15 | ||
| Living | 306 (57.1) | 280 (69.1) | |
| Deceased | 230 (42.9) | 125 (30.9) |
All data are number of patients (%) unless otherwise indicated.
Significant p values in bold font.
*Tumor stage was determined according to American Joint Committee onCancer v.7.0.
†For patients without surgery but with chemotherapy, radiation or chemoradiation treatment.
‡Others refer to adenosquamous carcinoma, bonchioalveolar carcinoma and large-cell carcinoma.
ECOG, Eastern Cooperative Oncology Group; SD, standard deviation.