Table 1.
Descriptive Characteristics of the Study Population
| Characteristic | Entire Cohort (n = 1070) | Training Set: Japanese Cohort (n = 557) | Validation Set: Korean Cohort (n = 513) | P |
|---|---|---|---|---|
| Age, mean (SD), y | 20.2 (12.9) | 20.6 (13.5) | 18.5 (10.4) | .006 |
| Age, No. (%) | ||||
| ≤12 y | 265 (24.8) | 136 (24.4) | 129 (25.1) | .026 |
| 13‐19 y | 482 (45.0) | 236 (42.4) | 246 (48.0) | |
| 20‐39 y | 242 (22.6) | 131 (23.5) | 111 (21.6) | |
| ≥40 y | 81 (7.6) | 54 (9.7) | 27 (5.3) | |
| Sex, No. (%) | ||||
| Male | 677 (63.3) | 344 (61.8) | 333 (64.9) | .285 |
| Female | 393 (36.7) | 213 (38.2) | 180 (35.1) | |
| Tumor size, mean (SD), cm | 9.8 (4.1) | 9.7 (4.1) | 9.9 (4.1) | .329 |
| Tumor size, No. (%) | ||||
| ≤8 cm | 450 (42.1) | 246 (44.2) | 204 (39.8) | .145 |
| >8 cm | 620 (57.9) | 311 (55.8) | 309 (60.2) | |
| Location, No. (%) | ||||
| Distal extremity | 70 (6.5) | 42 (7.5) | 28 (5.5) | .520 |
| Distal femur | 476 (44.5) | 251 (45.1) | 225 (43.9) | |
| Proximal tibia/fibula | 304 (28.4) | 151 (27.1) | 153 (29.8) | |
| Proximal humerus | 96 (9.0) | 47 (8.4) | 49 (9.6) | |
| Proximal femur | 77 (7.2) | 38 (6.8) | 39 (7.6) | |
| Trunk | 47 (4.4) | 28 (5.0) | 19 (3.7) | |
| Pathologic fracture, No. (%) | ||||
| No | 978 (91.4) | 516 (92.6) | 462 (90.1) | .132 |
| Yes | 92 (8.6) | 41 (7.4) | 51 (9.9) | |
| Histologic response (tumor necrotic rate), No. (%) | ||||
| Grade 1 (<50%) | 244 (22.8) | 144 (25.9) | 100 (19.5) | .013 |
| Grade 2 (50%‐89%) | 357 (33.4) | 168 (30.2) | 189 (36.8) | |
| Grade 3 (90%‐99%) | 322 (30.1) | 176 (31.6) | 146 (28.5) | |
| Grade 4 (100%) | 147 (13.7) | 69 (12.4) | 78 (15.2) |
Abbreviation: SD, standard deviation.