Table 3.
Multivariable analysis of prognostic factors for OS, PFS, LRFS, and DMFS in training cohort
| Characteristic | HR | 95% CI | p-value |
|---|---|---|---|
| Overall survival | |||
| Age | 1.736 | 1.510-1.996 | < 0.001 |
| Sex | 1.613 | 1.349-1.930 | < 0.001 |
| T category | |||
| T2 vs. T1 | 1.371 | 0.935-2.012 | 0.106 |
| T3 vs. T1 | 1.768 | 1.234-2.532 | 0.002 |
| T4 vs. T1 | 2.453 | 1.702-3.534 | < 0.001 |
| N category | |||
| N1 vs. N0 | 1.263 | 0.974-1.638 | 0.078 |
| N2 vs. N0 | 1.751 | 1.356-2.263 | < 0.001 |
| N3 vs. N0 | 2.623 | 1.948-3.531 | < 0.001 |
| PLN(+) vs. N0 | 3.951 | 2.807-5.561 | < 0.001 |
| EBV DNA level | |||
| 1,000-9,999 vs. < 1,000 | 1.417 | 1.121-1.792 | 0.004 |
| 10,000-99,999 vs. < 1,000 | 2.619 | 2.102-3.263 | < 0.001 |
| 100,000-999,999 vs. < 1,000 | 3.242 | 2.556-4.111 | < 0.001 |
| ≥ 1,000,000 vs. < 1,000 | 5.052 | 3.777-6.757 | < 0.001 |
| Progression-free survival | |||
| Age | 1.250 | 1.123-1.392 | < 0.001 |
| Sex | 1.378 | 1.205-1.575 | < 0.001 |
| T category | |||
| T2 vs. T1 | 1.602 | 1.176-2.183 | 0.003 |
| T3 vs. T1 | 1.909 | 1.424-2.558 | < 0.001 |
| T4 vs. T1 | 2.362 | 1.751-3.186 | < 0.001 |
| N category | |||
| N1 vs. N0 | 1.296 | 1.062-1.582 | 0.011 |
| N2 vs. N0 | 1.563 | 1.281-1.907 | < 0.001 |
| N3 vs. N0 | 1.985 | 1.564-2.520 | < 0.001 |
| PLN(+) vs. N0 | 4.225 | 3.224-5.538 | < 0.001 |
| EBV DNA level | |||
| 1,000-9,999 vs. < 1,000 | 1.392 | 1.168-1.661 | < 0.001 |
| 10,000-99,999 vs. < 1,000 | 2.570 | 2.174-3.037 | < 0.001 |
| 100,000-999,999 vs. < 1,000 | 3.225 | 2.681-3.880 | < 0.001 |
| ≥ 1,000,000 vs. < 1,000 | 5.303 | 4.191-6.710 | < 0.001 |
| Locoregional relapse-free survival | |||
| Age | 1.059 | 0.884-1.268 | 0.537 |
| Sex | 1.243 | 0.998-1.548 | 0.052 |
| T category | |||
| T2 vs. T1 | 2.501 | 1.426-4.387 | 0.001 |
| T3 vs. T1 | 2.382 | 1.382-4.106 | 0.002 |
| T4 vs. T1 | 2.640 | 1.513-4.607 | 0.001 |
| N category | |||
| N1 vs. N0 | 1.145 | 0.848-1.546 | 0.377 |
| N2 vs. N0 | 1.090 | 0.801-1.484 | 0.583 |
| N3 vs. N0 | 0.912 | 0.595-1.399 | 0.674 |
| PLN (+) vs. N0 | 3.168 | 2.059-4.875 | < 0.001 |
| EBV DNA level | |||
| 1,000-9,999 vs. < 1,000 | 1.365 | 1.028-1.814 | 0.032 |
| 10,000-99,999 vs. < 1,000 | 2.355 | 1.794-3.092 | < 0.001 |
| 100,000-999,999 vs. < 1,000 | 3.358 | 2.497-4.518 | < 0.001 |
| ≥ 1,000,000 vs. < 1,000 | 3.250 | 2.075-5.091 | < 0.001 |
| Distant metastasis-free survival | |||
| Age | 1.193 | 1.046-1.361 | 0.008 |
| Sex | 1.506 | 1.271-1.784 | < 0.001 |
| T category | |||
| T2 vs. T1 | 1.195 | 0.827-1.727 | 0.343 |
| T3 vs. T1 | 1.638 | 1.163-2.307 | 0.005 |
| T4 vs. T1 | 1.899 | 1.337-2.697 | < 0.001 |
| N category | |||
| N1 vs. N0 | 1.599 | 1.208-2.116 | 0.001 |
| N2 vs. N0 | 2.062 | 1.562-2.723 | < 0.001 |
| N3 vs. N0 | 2.866 | 2.095-3.920 | < 0.001 |
| PLN (+) vs. N0 | 6.060 | 4.305-8.531 | < 0.001 |
| EBV DNA level | |||
| 1,000-9,999 vs. < 1,000 | 1.577 | 1.250-1.991 | < 0.001 |
| 10,000-99,999 vs. < 1,000 | 3.104 | 2.493-3.863 | < 0.001 |
| 100,000-999,999 vs. < 1,000 | 4.092 | 3.233-5.180 | < 0.001 |
| ≥ 1,000,000 vs. < 1,000 | 7.166 | 5.387-9.532 | < 0.001 |
A Cox proportional hazard model was used to conduct multivariate analyses. All variables were transformed into categorical variables. HRs were calculated for age (> 46 years vs. ≤ 46 years), sex (male vs. female), T category, N category, and EBV DNA level. OS, overall survival; PFS, progression-free survival; LRFS, locoregional relapse-free survival; DMFS, distant metastasis-free survival; HR, hazard ratio; CI, confidence interval; EBV, Epstein-Barr virus; PLN, parotid lymph node.