Table 1 Baseline characteristics of the training, internal validation and external validation sets
Variables | Training set | Internal validation set | External validation set |
|---|---|---|---|
| Â | n = 5930 (%) | n = 2540 (%) | n = 473 (%) |
Age | |||
 ≤73 | 3593 (60.6) | 1585 (62.4) | 345 (72.9) |
 73–85 | 1713 (28.9) | 723 (28.5) | 110 (23.3) |
 >85 | 624 (10.5) | 232 (9.1) | 18 (3.8) |
Race | |||
 White | 4582 (77.3) | 1993 (78.5) | 0 (0.0) |
 Black | 840 (14.2) | 330 (13.0) | 0 (0.0) |
 Other | 508 (8.6) | 217 (8.5) | 473 (100.0) |
Gender | |||
 Male | 2683 (45.2) | 1192 (46.9) | 255 (53.9) |
 Female | 3247 (54.8) | 1348 (53.1) | 218 (46.1) |
Differentiation | |||
 Well | 410 (6.9) | 184 (7.2) | 5 (1.1) |
 Moderate | 4083 (68.9) | 1759 (69.3) | 432 (91.3) |
 Poor | 1199 (20.2) | 482 (19.0) | 36 (7.6) |
 Undifferentiation | 238 (4.0) | 115 (4.5) | 0 (0.0) |
Stage_T | |||
 T0/1 | 504 (8.5) | 215 (8.5) | 6 (1.3) |
 T2 | 847 (14.3) | 341 (13.4) | 91 (19.2) |
 T3 | 3654 (61.6) | 1559 (61.4) | 286 (60.5) |
 T4 | 925 (15.6) | 425 (16.7) | 90 (19.0) |
Stage_N | |||
 N0 | 3389 (57.2) | 1436 (56.5) | 308 (65.1) |
 N1 | 1520 (25.6) | 652 (25.7) | 118 (25.0) |
 N2 | 1021 (17.2) | 452 (17.8) | 47 (9.9) |
Stage_M | |||
 M0 | 5128 (86.5) | 2199 (86.6) | 439 (92.8) |
 M1 | 802 (13.5) | 341 (13.4) | 34 (7.2) |
AJCC-TNM classification | |||
 0/I | 1140 (19.2) | 465 (18.3) | 69 (14.6) |
 II | 2145 (36.2) | 932 (36.7) |  |
 III | 1843 (31.1) | 802 (31.6) | 132 (27.9) |
 IV | 802 (13.5) | 341 (13.4) | 34 (7.2) |
CEA | |||
 Normal | 3516 (59.3) | 1507 (59.3) | 270 (57.1) |
 Elevate | 2414 (40.7) | 1033 (40.7) | 203 (42.9) |
Chemotherapy | |||
 Yes | 2021 (34.1) | 894 (35.2) | 116 (24.5) |
 No | 3909 (65.9) | 1646 (64.8) | 357 (75.5) |
Tumour size (cm) | |||
 ≤3.3 | 1644 (27.7) | 680 (26.8) | 110 (23.2) |
 3.3–7.5 | 3421 (57.7) | 1489 (58.6) | 319 (67.4) |
 >7.5 | 865 (14.6) | 371 (14.6) | 44 (9.3) |
LNR | |||
 ≤4.9% | 3785 (63.8) | 1624 (63.9) | 325 (68.7) |
 4.9–32.8% | 1523 (25.7) | 666 (26.2) | 96 (20.3) |
 >32.8% | 622 (10.5) | 250 (9.8) | 52 (11.0) |
Perineural invasion | |||
 No | 5275 (89.0) | 2230 (87.8) | 461 (97.5) |
 Yes | 655 (11.1) | 310 (12.2) | 12 (2.5) |