Basic characteristics of patients in this study
| Variables | Training cohort | Validation cohort | P value |
| Number of patients, n (%) | 1803 (70) | 773 (30) | |
| Age, median (IQR) | 71.00 (64.00–78.00) | 71.00 (63.00–78.00) | 0.710 |
| Sex, n (%) | 0.150 | ||
| Female | 711 (39.4) | 329 (42.6) | |
| Male | 1092 (60.6) | 444 (57.4) | |
| Race, n (%) | 0.045 | ||
| Black | 80 (4.4) | 50 (6.5) | |
| Other | 169 (9.4) | 83 (10.7) | |
| White | 1554 (86.2) | 640 (82.8) | |
| Marital status, n (%) | 0.656 | ||
| Married | 1565 (86.8) | 677 (87.6) | |
| Others | 67 (3.7) | 31 (4.0) | |
| Single | 171 (9.5) | 65 (8.4) | |
| Year, n (%) | 0.813 | ||
| 2004–2006 | 346 (19.2) | 159 (20.6) | |
| 2007–2009 | 439 (24.3) | 181 (23.4) | |
| 2010–2012 | 479 (26.6) | 198 (25.6) | |
| 2013–2015 | 539 (29.9) | 235 (30.4) | |
| Site, n (%) | 0.609 | ||
| Renal pelvis | 1152 (63.9) | 485 (62.7) | |
| Ureter | 651 (36.1) | 288 (37.3) | |
| Grade, n (%) | 0.481 | ||
| Grade I | 47 (2.6) | 16 (2.1) | |
| Grade II | 149 (8.3) | 69 (8.9) | |
| Grade III | 559 (31.0) | 258 (33.4) | |
| Grade IV | 1048 (58.1) | 430 (55.6) | |
| Size, n (%) | 0.188 | ||
| 2–4 | 559 (31.0) | 268 (34.7) | |
| <2 | 262 (14.5) | 106 (13.7) | |
| ≥4 | 982 (54.5) | 399 (51.6) | |
| Laterality, n (%) | 0.551 | ||
| Left | 995 (55.2) | 416 (53.8) | |
| Right | 808 (44.8) | 357 (46.2) | |
| Surgery, n (%) | 0.203 | ||
| No/unknown | 9 (0.5) | 8 (1.0) | |
| Yes | 1794 (99.5) | 765 (99.0) | |
| Radiotherapy, n (%) | 0.931 | ||
| No/unknown | 1676 (93.0) | 720 (93.1) | |
| Yes | 127 (7.0) | 53 (6.9) | |
| Chemotherapy, n (%) | 0.938 | ||
| No/unknown | 1243 (68.9) | 531 (68.7) | |
| Yes | 560 (31.1) | 242 (31.3) | |
| Distant metastasis, n (%) | 0.053 | ||
| M0 | 1652 (91.6) | 689 (89.1) | |
| M1 | 151 (8.4) | 84 (10.9) | |
| LNE, median (IQR) | 3.00 (1.00–7.00) | 3.00 (1.00–7.00) | 0.627 |
| LNP, median (IQR) | 0.00 (0.00–1.00) | 0.00 (0.00–1.00) | 0.542 |
| LNR, median (IQR) | 0.00 (0.00–0.50) | 0.00 (0.00–0.33) | 0.546 |
LNE, lymph nodes examined; LNP, lymph nodes positive; LNR, lymph nodes ratio.