| Training set (n = 86) | Internal validation set (n = 226) | External validation set (n = 246) | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
NPC1 (n = 37) | NPC2 (n = 33) | NPC3 (n = 16) | P value* | NPC1 (n = 115) | NPC2 (n = 75) | NPC3 (n = 36) | P value* | NPC1 (n = 104) | NPC2 (n = 93) | NPC3 (n = 49) | P value* | |
Age, years | 47.03 | 47.91 | 48.81 | 0.4199 | 47.09 | 45.88 | 45.92 | 0.8134 | 50.23 | 51.63 | 48.07 | 0.4408 |
Sex, male | 22 (59%) | 27 (82%) | 13 (81%) | 0.0760 | 86 (75%) | 56 (75%) | 29 (80%) | 0.757 | 73 (70%) | 66 (71%) | 36 (73%) | 0.9156 |
WHO pathological type | 0.1541 | 0.5689 | NA | |||||||||
 Undifferentiated non-keratinising | 0 | 1 | 0 |  | 2 | 0 | 0 |  | NA | NA | NA |  |
 Differentiated non-keratinising | 1 | 0 | 2 |  | 3 | 2 | 0 |  | NA | NA | NA |  |
 Keratinising squamous cell | 36 | 32 | 14 |  | 110 | 73 | 36 |  | NA | NA | NA |  |
T stage | 0.7670 | 0.5842 | 0.2508 | |||||||||
 T1 | 13 | 11 | 7 |  | 22 | 7 | 6 |  | 32 | 29 | 14 |  |
 T2 | 24 | 22 | 9 |  | 14 | 13 | 7 |  | 16 | 27 | 8 |  |
 T3 | 0 | 0 | 0 |  | 35 | 26 | 10 |  | 21 | 19 | 13 |  |
 T4 | 0 | 0 | 0 |  | 44 | 29 | 13 |  | 35 | 20 | 13 |  |
N stage | 0.2327 | 0.797 | 0.9027 | |||||||||
 N0 | 10 | 7 | 1 |  | 13 | 8 | 5 |  | 22 | 16 | 11 |  |
 N1 | 27 | 26 | 15 |  | 43 | 26 | 11 |  | 34 | 35 | 14 |  |
 N2 | 0 | 0 | 0 |  | 37 | 26 | 9 |  | 37 | 32 | 19 |  |
 N3 | 0 | 0 | 0 |  | 22 | 15 | 11 |  | 1 | 1 | 2 |  |
TNM stage | NA | 0.7387 | NA | |||||||||
 I | 0 | 0 | 0 |  | 8 | 2 | 2 |  | NA | NA | NA |  |
 II | 37 | 33 | 16 |  | 0 | 0 | 0 |  | NA | NA | NA |  |
 III | 0 | 0 | 0 |  | 46 | 32 | 13 |  | NA | NA | NA |  |
 IV | 0 | 0 | 0 |  | 61 | 41 | 21 |  | NA | NA | NA |  |
Disease-free survival | 0.263a | 0.0363a | 0.6443a | |||||||||
 Relapses or deaths | 5 (14%) | 9 (27%) | 2 (12%) |  | 40 (28%) | 44 (39%) | 11 (19%) |  | 37 (36%) | 35 (38%) | 15 (31%) |  |
 5 year | 86% | 73% | 88% |  | 72% | 61% | 81% |  | 64% | 62% | 69% |  |
Distant metastasis-free survival | 0.0215a | 0.0449a | 0.0476a | |||||||||
 Distant metastases | 0 (0.0%) | 6 (18%) | 1 (6.0%) |  | 24 (17%) | 34 (30%) | 8 (13%) |  | 13 (12%) | 19 (20%) | 3 (6.0%) |  |
 5-year | 100% | 82% | 94% |  | 83% | 70% | 87% |  | 88% | 80% | 94% |  |
Overall survival | 0.6549a | 0.1708a | 0.5951a | |||||||||
 Deaths | 4 (11%) | 5 (15%) | 1 (6.0%) |  | 32 (23%) | 32 (28%) | 10 (17%) |  | 29 (28%) | 29 (31%) | 12 (24%) |  |
 5-year | 89% | 85% | 94% |  | 77% | 72% | 83% |  | 82% | 69% | 76% |  |