Characteristics | Training set (n = 46) | P value | Validation set (n = 25) | P value | ||
---|---|---|---|---|---|---|
 | ORN | Metastasis |  | ORN | Metastasis |  |
Number of patients (n) | 25 (54.3%) | 21 (45.7%) | Â | 14 (56.0%) | 11 (44.0%) | Â |
Gender | ||||||
 Male | 19 (76.0%) | 15 (71.4%) | 0.725 | 11 (78.6%) | 8 (72.7%) | 0.739 |
 Female | 6 (24.4%) | 6 (28.6%) |  | 3 (21.4%) | 3 (27.3%) |  |
 Age (years) | 50.0 ± 10.8 | 49.1 ± 11.7 | 0.790 | 51.8 ± 10.7 | 48.9 ± 10.5 | 0.735 |
Over stagea | ||||||
 I | 2 (8.0%) | 1 (4.8%) | 0.886 | 1 (7.1%) | 1 (9.1%) | 0.901 |
 II | 10 (40.0%) | 7 (33.3%) |  | 4 (28.6%) | 2 (18.2%) |  |
 III | 8 (32.0%) | 6 (28.6%) |  | 6 (42.9%) | 4 (36.4%) |  |
 IVA | 3 (12.0%) | 4 (19.0%) |  | 2 (14.3%) | 2 (18.2%) |  |
 IVB | 2 (8.0%) | 3 (14.3%) |  | 1 (7.1%) | 2 (18.2%) |  |
 Involvement multiple lesions | 19 (76.0%) | 16 (76.2%) |  | 10 (71.4%) | 9 (81.8%) |  |
 Overall RT dose (Gy) | 69.5 ± 12.3 | 67.4 ± 17.8 | 0.617 | 73.2 ± 9.6 | 73.0 ± 10.9 | 0.637 |
 Concurrent chemotherapy | 22 (88.0%) | 20 (95.2%) | 0.373 | 13 (92.9%) | 10 (90.9%) | 0.476 |
 Interval time from first RT to lesion detection (mouth) | 36.1 ± 26.3 | 41.3 ± 25.6 | 0.498 | 31.3 ± 22.5 | 32.1 ± 16.2 | 0.060 |
 Cervical lymphadenopathyb | 2 (8.0%) | 7 (33.3%) | 0.033 | 0 (0.0%) | 4 (36.4%) | 0.006 |
 Radiation-induced brain necrosis | 2 (8.0%) | 1 (4.8%) | 0.654 | 1 (7.1%) | 0 (0%) | 0.275 |