Table 1.
Demographics for training, independent validation, and two validation cohorts.
| MDACC training | MDACC validation | UMCG validation | TCIA PMH validation | p-value | |||||
|---|---|---|---|---|---|---|---|---|---|
| N | 2241 | 786 | 1087 | 497 | |||||
| Age (mean (SD)) | 59.48 | (10.14) | 59.74 | (9.74) | 64.17 | (10.56) | 60.16 | (9.90) | <0.001 |
| Sex (%) | |||||||||
| Female | 373 | (17) | 130 | (17) | 324 | (30) | 105 | (21) | <0.001 |
| Male | 1868 | (83) | 656 | (83) | 763 | (70) | 392 | (79) | |
| T stage (%) | <0.001 | ||||||||
| T0 | 53 | (2) | 17 | (2) | 2 | (0) | 0 | (0) | |
| T1 | 507 | (23) | 178 | (23) | 196 | (18) | 90 | (18) | |
| T2 | 788 | (35) | 288 | (37) | 262 | (24) | 162 | (33) | |
| T3 | 453 | (20) | 162 | (21) | 251 | (23) | 146 | (29) | |
| T4 | 414 | (18) | 136 | (17) | 376 | (35) | 99 | (20) | |
| Tx | 26 | (1) | 5 | (1) | 0 | (0) | 0 | (0) | |
| N stage (%) | <0.001 | ||||||||
| N0 | 487 | (22) | 152 | (19) | 435 | (40) | 82 | (16) | |
| N1 | 276 | (12) | 116 | (15) | 130 | (12) | 48 | (10) | |
| N2a-b | 1081 | (48) | 356 | (45) | 279 | (26) | 202 | (41) | |
| N2c | 318 | (14) | 141 | (18) | 202 | (19) | 123 | (25) | |
| N3 | 79 | (4) | 21 | (3) | 37 | (3) | 42 | (8) | |
| HPV status (%) | <0.001 | ||||||||
| Negative | 617 | (28) | 288 | (37) | 912 | (84) | 142 | (29) | |
| Positive | 990 | (44) | 498 | (63) | 175 | (16) | 355 | (71) | |
| Unknown | 634 | (28) | 0 | (0) | 0 | (0) | 0 | (0) | |
| Site (%) | <0.001 | ||||||||
| Oropharynx | 1382 | (62) | 462 | (59) | 328 | (30) | 497 | (100) | |
| Larynx | 420 | (19) | 179 | (23) | 446 | (41) | 0 | (0) | |
| Oral Cavity | 314 | (14) | 95 | (12) | 263 | (24) | 0 | (0) | |
| Hypopharynx | 50 | (2) | 32 | (4) | 26 | (2) | 0 | (0) | |
| Nasopharynx | 22 | (1) | 0 | (0) | 23 | (2) | 0 | (0) | |
| Unkown primary | 53 | (2) | 18 | (2) | 1 | (0) | 0 | (0) | |
| AJCC8th stage (%) | <0.001 | ||||||||
| I | 605 | (27) | 271 | (34) | 159 | (15) | 156 | (31) | |
| II | 368 | (16) | 157 | (20) | 163 | (15) | 137 | (28) | |
| III | 349 | (16) | 143 | (18) | 247 | (23) | 106 | (21) | |
| IVa | 472 | (21) | 206 | (26) | 491 | (45) | 87 | (18) | |
| IVb | 29 | (1) | 9 | (1) | 27 | (2) | 11 | (2) | |
| Unknown | 418 | (19) | 0 | (0) | 0 | (0) | 0 | (0) | |
| Performance score (%) | <0.001 | ||||||||
| 0 | 850 | (38) | 397 | (51) | 619 | (57) | 323 | (65) | |
| 1 | 620 | (28) | 319 | (41) | 350 | (32) | 125 | (25) | |
| >2 | 181 | (8) | 70 | (9) | 118 | (11) | 49 | (10) | |
| Unknown | 590 | (26) | 0 | (0) | 0 | (0) | 0 | (0) | |
| Smoking status (%) | <0.001 | ||||||||
| Never | 773 | (34) | 301 | (38) | 175 | (16) | 144 | (29) | |
| Former | 998 | (45) | 360 | (46) | 457 | (42) | 198 | (40) | |
| Current | 453 | (20) | 125 | (16) | 427 | (39) | 155 | (31) | |
| Unknown | 17 | (1) | 0 | (0) | 28 | (3) | 0 | (0) | |
| Pack years (mean (SD)) | 22.03 | (33.69) | 20.01 | (28.19) | 30.77 | (23.90) | 24.35 | (24.67) | <0.001 |
| Chemotherapy (%) | <0.001 | ||||||||
| None | 446 | (20) | 115 | (15) | 696 | (64) | 254 | (51) | |
| Concurrent | 1060 | (47) | 410 | (52) | 389 | (36) | 243 | (49) | |
| Induction | 218 | (10) | 100 | (13) | 1 | (0) | 0 | (0) | |
| Induction + concurrent | 480 | (21) | 161 | (20) | 1 | (0) | 0 | (0) | |
| Unknown | 37 | (2) | 0 | (0) | 0 | (0) | 0 | (0) | |
| Technique (%) | <0.001 | ||||||||
| 3DCRT | 211 | (9) | 9 | (1) | 14 | (1) | 0 | (0) | |
| IMRT | 1496 | (67) | 450 | (57) | 517 | (48) | 497 | (100) | |
| VMAT | 466 | (21) | 292 | (37) | 401 | (37) | 0 | (0) | |
| IMPT | 68 | (3) | 35 | (4) | 111 | (10) | 0 | (0) | |
| Unknown | 0 | (0) | 0 | (0) | 44 | (4) | 0 | (0) | |
| Radiotherapy type (%) | <0.001 | ||||||||
| Primary | 1727 | (77) | 644 | (82) | 852 | (78) | 497 | (100) | |
| Post-operative | 251 | (11) | 40 | (5) | 230 | (21) | 0 | (0) | |
| Unknown | 263 | (12) | 102 | (13) | 5 | (0) | 0 | (0) | |
| Mortality events (%) | 635 | (28) | 148 | (19) | 402 | (37) | 206 | (41) | <0.001 |
| Local failure events (%) | 233 | (10) | 70 | (9) | 149 | (14) | 46 | (9) | <0.001 |
| Regional failure events (%) | 182 | (8) | 48 | (6) | 105 | (10) | 31 | (6) | 0.005 |
Abbreviations: SD: standard deviation; HPV, human papilloma virus; 3DCRT, three-dimensional conformal radiotherapy; IMRT, intensity-modulated radiotherapy; VMAT, volumetric-modulated arc therapy; IMPT, intensity-modulated proton therapy.