Table 1.
Baseline characteristics of patients with stage IV colorectal cancer in training, internal validation, and external validation cohorts
| Characteristic | Training cohort | Internal validation cohort | External validation cohort |
|---|---|---|---|
| (n = 11,398) | (n = 4,885) | (n = 501) | |
| Age (years) | |||
| <50 | 1,959 (17.2) | 895 (18.3) | 117 (23.4) |
| 50–74 | 7,066 (62.0) | 2,967 (60.7) | 327 (65.3) |
| ≥75 | 2,373 (20.8) | 1,023 (20.9) | 57 (11.3) |
| Sex | |||
| Female | 5,343 (46.9) | 2,212 (45.3) | 186 (37.1) |
| Male | 6,055 (53.1) | 2,673 (54.7) | 315 (62.9) |
| Race | |||
| Black | 1,687 (14.8) | 700 (14.3) | – |
| White | 8,645 (75.8) | 3,727 (76.3) | – |
| Others | 1,066 (9.4) | 458 (9.4) | 501 (100) |
| Tumor location | |||
| Right colon | 5,135 (45.1) | 2,209 (45.2) | 120 (24.0) |
| Left colon | 4,472 (39.2) | 1,935 (39.6) | 185 (36.9) |
| Rectum | 1,791 (15.7) | 741 (15.2) | 196 (39.1) |
| Tumor size | |||
| <50 mm | 4,748 (41.7) | 1,977(40.5) | 338 (67.5) |
| 50–69 mm | 3,630 (31.8) | 1,668 (34.1) | 100 (20.0) |
| ≥70 mm | 3,020 (26.5) | 1,240 (25.4) | 63 (12.6) |
| T stage | |||
| T1 | 618 (5.4) | 293 (6.0) | 1 (0.2) |
| T2 | 365 (3.2) | 142 (2.9) | 13 (2.6) |
| T3 | 5,797 (50.9) | 2,548 (52.2) | 373(74.5) |
| T4 | 4,618 (40.5) | 1,902 (38.9) | 114 (22.8) |
| N stage | |||
| N0 | 2,288 (20.1) | 1,007 (20.6) | 140(27.9) |
| N1 | 4,445 (39.0) | 1,915 (39.2) | 236 (47.1) |
| N2 | 4,665 (40.9) | 1,963 (40.2) | 125 (25.0) |
| Histological differentiation | |||
| Highly | 544 (4.8) | 228 (4.7) | 84 (16.8) |
| Moderate | 7,342 (64.4) | 3,147 (64.4) | 376 (75.0) |
| Poorly | 2,816 (24.7) | 1,222(25.0) | 33 (6.6) |
| Undifferentiated | 696 (6.1) | 288 (5.9) | 8 (1.6) |
| Number of LNs examined | |||
| <12 | 3,338 (29.3) | 1,478 (30.3) | 263 (52.5) |
| ≥12 | 8,060 (70.7) | 3,407 (69.7) | 238 (47.5) |
| Organ metastasis | |||
| 0 | 2,425 (21.3) | 10,080 (20.6) | 268 (53.5) |
| 1 | 7,384 (64.8) | 3,186 (65.2) | 178 (35.5) |
| >1 | 1,589 (13.9) | 691 (14.1) | 55 (11.0) |
| Radiotherapy | |||
| No | 10,428 (91.5) | 4,495 (92.0) | 491 (98.0) |
| Yes | 970 (8.5) | 390 (8.0) | 10 (2.0) |
| Chemotherapy | |||
| No | 3,378 (29.6) | 1,427 (29.2) | 366 (73.1) |
| Yes | 8,020 (70.4) | 3,458 (70.8) | 135 (26.9) |