Table 1. Baseline patient and treatment characteristics, by p16 status.
CRT = Chemoradiation, RT = Radiation, UND = unilateral neck dissection
| Characteristic | p16-positive (n=142) | p16-negative (n= 40) | p-value |
| Mean age at diagnosis | 55.7 | 59.5 | 0.02 |
| Gender | <0.01 | ||
| Male | 117 (82%) | 23 (58%) | |
| Female | 25 (18%) | 17 (43%) | |
| T Stage | 0.37 | ||
| T1 | 44 (31%) | 8 (20%) | |
| T2 | 67 (47%) | 19 (48%) | |
| T3 | 24 (17%) | 11 (28%) | |
| T4 | 7 (5%) | 2 (5%) | |
| N Stage | < 0.01 | ||
| N0 | 26 (18%) | 18 (45%) | |
| N1 | 26 (18%) | 5 (13%) | |
| N2 | 75 (53%) | 15 (38%) | |
| N3 | 15 (11%) | 2 (5%) | |
| Stage | 0.03 | ||
| I | 3 (2%) | 4 (10%) | |
| II | 18 (13%) | 9 (23%) | |
| III | 28 (20%) | 10 (25%) | |
| IVA | 78 (55%) | 15 (38%) | |
| IVB | 15 (11%) | 2 (5%) | |
| Smoking | < 0.01 | ||
| Current/quit less than 1 year | 42 (30%) | 31 (78%) | |
| Former (quit more than 1 year) | 55 (39%) | 2 (5%) | |
| Never | 45 (32%) | 7 (18%) | |
| Radiation | |||
| < 60 Gy | 66 (46%) | 21 (53%) | 0.5 |
| 61-70 Gy | 76 (54%) | 19 (48%) | |
| Unilateral | 53 (37%) | 17 (43%) | 0.56 |
| Bilateral | 89 (63%) | 23 (58%) | |
| RT alone | 83 (59%) | 29 (73%) | 0.11 |
| CRT | 59 (42%) | 11 (28%) | |
| Chemotherapy | 0.61 | ||
| Cisplatin-based | 47 (80%) | 8 (73%) | |
| Carboplatin-based | 12 (20%) | 2 (27%) | |
| Surgery | 0.51 | ||
| None | 128 (90%) | 39 (98%) | |
| Primary resection | 1 (< 1%) | 0 | |
| Post-RT primary and UND | 1 (<1%) | 0 | |
| Post-RT UND | 12 (9%) | 1 (3%) | |