Table 2.
Univariate and multivariate analysis of variables correlated with distant metastasis, progression-free survival and overall survival
| Distant metastasis | Progression-free survival | Overall survival | ||||
|---|---|---|---|---|---|---|
| Characteristics | UVA | MVA | UVA | MVA | UVA | MVA |
| HR (95% CI) | HR (95% CI) | HR (95% CI) | HR (95% CI) | HR (95% CI) | HR (95% CI) | |
| Age (continuous value) | 1.013 (0.979–1.049) | 1.034 (1.007–1.061) | 1.036 (1.008–1.065) | 1.058 (1.026–1.091) | 1.074 (1.040–1.109) | |
| Sex (female) | 1.119 (0.473–2.648) | 1.935 (0.906–4.136) | 1.486 (0.679–3.254) | 1.645 (0.679–3.986) | ||
| WHO, IIB VS others | 0.559 (0.211–1.476) | 0.740 (0.332–1.649) | 1.013 (0.356–2.886) | |||
| T stage, T1–T2 vs T3–T4 | 0.237 (0.104–0.544) | 0.537 (0.348–0.828) | 0.671 (0.462–0.824) | 0.415 (0.223–0.773) | 0.680 (0.482–0.960) | 0.764 (0.534–1.091) |
| N stage, N0–N2 vs N3 | 0.748 (0.316–1.769) | 0.917 (0.672–1.253) | 1.045 (0.727–1.502) | |||
| Detectable pre-IMRT EBV DNAa | 2.683 (1.134–6.348) | 1.538 (0.611–3.876) | 2.357 (1.263–4.397) | 1.445 (0.736–2.836) | 2.256 (1.070–4.753) | 1.450 (0.644–3.265) |
| Detectable mid-IMRT EBV DNAa | 4.338 (1.641–11.472) | 1.657 (0.571–4.803) | 3.717 (1.658–8.333) | 1.457 (0.597–3.554) | 2.660 (0.927–7.632) | |
| Detectable post-IMRT EBV DNAa | 20.806 (8.258–52.420) | 14.331 (5.124–40.078) | 16.011 (1.309–35.071) | 12.167 (5.133–28.840) | 13.109 (5.631–30.519) | 16.956 (6.511–44.157) |
UVA = univariate analysis, MVA = multivariate analysis, HR = hazard ratio, CI = confidence interval, WHO = World Health Organization classification, pre-IMRT EBV DNA = plasma EBV DNA level before treatment, mid-IMRT EBV DNA = plasma EBV DNA level on the fifth week of radiation, post-IMRT EBV DNA = plasma EBV DNA level at 3 months after completion of treatment. aDetectable versus undetectable plasma EBV DNA.