Table 1. Characteristics of study cohorts.
| Variables | n (%) | P | |
| Training
cohort (N=624) |
Validation
cohort (N=307) |
||
| KPS, Karnofsky performance status; LN, lymph node; cTNM, clinical TNM stage; pTNM, pathological TNM stage. | |||
| Age (year) | 0.062 | ||
| <65 | 457 (73.2) | 206 (67.1) | |
| ≥65 | 167 (26.8) | 101 (32.9) | |
| Gender | 0.894 | ||
| Male | 526 (84.3) | 257 (83.7) | |
| Female | 98 (15.7) | 50 (16.3) | |
| KPS | 0.308 | ||
| 90−100 | 367 (58.8) | 192 (62.5) | |
| 70−80 | 257 (41.2) | 115 (37.5) | |
| Tumor location | 0.872 | ||
| Upper | 181 (29.0) | 84 (27.4) | |
| Middle | 310 (49.7) | 156 (50.8) | |
| Lower | 133 (21.3) | 67 (21.8) | |
| Differentiation | 0.871 | ||
| G1 | 119 (19.1) | 63 (20.5) | |
| G2 | 238 (38.1) | 115 (37.5) | |
| G3 | 267 (42.8) | 129 (42.0) | |
| Surgical margin | 0.056 | ||
| R0 | 586 (93.9) | 298 (97.1) | |
| R1/2 | 38 (6.1) | 9 (2.9) | |
| Vascular invasion | 0.779 | ||
| No | 508 (81.4) | 253 (82.4) | |
| Yes | 116 (18.6) | 54 (17.6) | |
| Neural invasion | 0.015 | ||
| No | 517 (82.9) | 233 (75.9) | |
| Yes | 107 (17.1) | 74 (24.1) | |
| Resected LN number | 0.544 | ||
| <20 | 276 (44.2) | 143 (46.6) | |
| ≥20 | 348 (55.8) | 164 (53.4) | |
| cTNM | 0.089 | ||
| I | 9 (1.4) | 5 (1.6) | |
| II | 167 (26.8) | 69 (22.5) | |
| III | 238 (38.1) | 104 (33.9) | |
| IV | 210 (33.7) | 129 (42.0) | |
| pTNM (8th) | 0.588 | ||
| I | 43 (6.9) | 23 (7.5) | |
| II | 202 (32.4) | 93 (30.3) | |
| III | 289 (46.3) | 151 (49.2) | |
| IV | 90 (14.4) | 40 (13.0) | |