Table 1. Characteristics of the study population.
| Variable | Training cohort (n=90), n (%) | Validation cohort (n=45), n (%) | Testing cohort (n=30), n (%) | P |
|---|---|---|---|---|
| Age (years) | 0.346 | |||
| <60 | 36 (40.0) | 19 (42.2) | 8 (26.7) | |
| ≥60 | 54 (60.0) | 26 (57.8) | 22 (73.3) | |
| Gender | 0.261 | |||
| Male | 66 (73.3) | 32 (71.1) | 26 (86.7) | |
| Female | 24 (26.7) | 13 (28.9) | 4 (13.3) | |
| Vital status | 0.564 | |||
| Alive | 35 (38.9) | 19 (42.2) | 15 (50.0) | |
| Dead | 55 (61.1) | 26 (57.8) | 15 (50.0) | |
| Tumor site | 0.987 | |||
| Upper | 21 (23.3) | 12 (26.7) | 6 (20.0) | |
| Middle | 11 (12.2) | 6 (13.3) | 5 (16.7) | |
| Lower | 42 (46.7) | 20 (44.4) | 13 (43.3) | |
| Overlap | 16 (17.8) | 7 (15.6) | 6 (20.0) | |
| Differentiation | 0.881 | |||
| Moderate | 55 (61.1) | 26 (57.8) | 19 (63.3) | |
| Poorly | 35 (38.9) | 19 (42.2) | 11 (36.7) | |
| TNM stage | 0.625 | |||
| I | 6 (6.7) | 2 (4.4) | 1 (3.3) | |
| II | 22 (24.4) | 9 (20.0) | 4 (13.3) | |
| III | 62 (68.9) | 34 (75.6) | 25 (83.3) | |
| T stage | 0.860 | |||
| T1 | 5 (5.6) | 4 (8.9) | 1 (3.3) | |
| T2 | 12 (13.3) | 5 (11.1) | 3 (10.0) | |
| T3 | 14 (15.6) | 4 (8.9) | 5 (16.7) | |
| T4 | 59 (65.6) | 32 (71.1) | 21 (70.0) | |
| N stage | 0.994 | |||
| N0 | 23 (25.6) | 9 (20.0) | 7 (23.3) | |
| N1 | 16 (17.8) | 8 (17.8) | 6 (20.0) | |
| N2 | 25 (27.8) | 14 (31.1) | 9 (30.0) | |
| N3 | 26 (28.9) | 14 (31.1) | 8 (26.7) | |
| Adjuvant therapy | 0.990 | |||
| None | 55 (61.1) | 25 (55.6) | 16 (53.3) | |
| Chemotherapy | 15 (16.7) | 8 (17.8) | 6 (20.0) | |
| Radiotherapy | 2 (2.2) | 1 (2.2) | 1 (3.3) | |
| Chemoradiotherapy | 18 (20.0) | 11 (24.4) | 7 (23.3) | |