Table 1 Characteristics of the patients in the training, internal validation and external validation cohorts
Characteristic | Training cohort (n = 329) | Internal validation cohort (n = 329) | External validation cohort (n = 315) | P |
|---|---|---|---|---|
Age, median (IQR) | 60.0 (51.0, 66.0) | 59.0 (51.0, 67.0) | 58 (50.0, 66.0) | 0.401 |
Sex, No. (%) | Â | Â | Â | 0.807 |
 Male | 189 (57.4) | 196 (59.6) | 188 (59.7) |  |
 Female | 140 (42.6) | 133 (40.4) | 127 (40.3) |  |
Primary tumor location, No. (%) | Â | Â | Â | 0.434 |
 Left-sided | 221 (67.2) | 213 (64.7) | 219 (69.5) |  |
 Right-sided | 108 (32.8) | 116 (35.3) | 96 (30.5) |  |
Preoperative CEA level, No. (%) | Â | Â | Â | 0.196 |
 Normal | 200 (60.80 | 197 (59.9) | 171 (54.3) |  |
 Elevated | 129 (39.2) | 132 (40.1) | 144 (45.7) |  |
Preoperative CA19-9 level, No. (%) | Â | Â | Â | 0.394 |
 Normal | 251 (76.3) | 247 (75.1) | 226 (71.7) |  |
 Elevated | 78 (23.7) | 82 (24.9) | 89 (28.3) |  |
Lymphadenectasis on CT, No. (%) | Â | Â | Â | 0.648 |
 < 10 mm | 153 (46.5) | 147 (44.7) | 135 (42.9) |  |
 ≥ 10 mm | 176 (53.5) | 182 (55.3) | 180 (57.1) |  |
Tumor differentiation, No. (%) | Â | Â | Â | 0.105 |
 Well or moderately | 264 (80.2) | 266 (80.9) | 235 (74.6) |  |
 Poorly or undifferentiated | 65 (19.8) | 63 (19.1) | 80 (25.4) |  |
VELIPI, No. (%) | Â | Â | Â | 0.661 |
 No | 192 (58.4) | 189 (57.4) | 173 (57.9) |  |
 Yes | 137 (41.6) | 140 (42.6) | 142 (45.1) |  |
Tumor size, cm, No. (%) | Â | Â | Â | 0.622 |
 < 4 | 144 (43.8) | 136 (41.3) | 142 (45.1) |  |
 ≥ 4 | 185 (56.20 | 193 (58.7) | 173 (54.9) |  |
pT stage, No. (%) | Â | Â | Â | 0.137 |
 pTis-T2 | 71 (21.6) | 69 (21.0) | 45 (14.3) |  |
 pT3 | 145 (44.1) | 145 (44.1) | 147 (46.7) |  |
 pT4 | 113 (34.3) | 115 (35.0) | 123 (39.0) |  |
Lymph node metastasis | Â | Â | Â | 0.479 |
 Yes | 147 (44.7) | 150 (46.6) | 155 (49.0) |  |
 No | 182 (55.3) | 179 (53.4) | 160 (51.0) |  |
PCS, median (IQR) | − 0.251 (− 0.505, 0.386) | − 0.244 (− 0.484, 0.210) | − 0.249 (− 0.395, 0.038) | 0.118 |