Endpoint | Variable | Estimate | HR† | 95% CI* |
Pvalue‡
|
---|
OS | Age | -0.403 | 0.668 | 0.450-0.993 | 0.046 |
| N stage | 0.312 | 1.366 | 1.037-1.799 | 0.027 |
| MPTD | 0.720 | 2.054 | 1.509-2.794 | < 0.001 |
FFS | N stage | 0.527 | 1.694 | 1.218-2.357 | 0.002 |
| MPTD | 0.713 | 2.040 | 1.426-2.919 | < 0.001 |
DMFS | N stage | 0.628 | 1.873 | 1.269-2.766 | 0.002 |
| MPTD | 0.563 | 1.757 | 1.155-2.671 | 0.008 |
LRFS | MPTD | 0.955 | 2.598 | 1.342-5.033 | 0.005 |
- †HR: Hazard ratio from Cox proportional hazards model; *CI, confidence interval; ‡
P values were calculated using an adjusted Cox proportional-hazards model. OS, overall survival; FFS, failure-free survival; DMFS, distant metastasis-free survival; LRFS, local relapse-free survival; MPTD, maximum primary tumor diameter. The following parameters were included in the model as the covariates for each analysis: age (≤ 45 vs. > 45 years), sex, chemotherapy (yes vs. no) and radiation technique (2-DRT vs. 3-DCRT). For analysis of OS, FFS and DMFS, the following additional covariates were introduced into the model: T stage (T1 vs. T2 vs. T3 vs. T4), N stage (N0 vs. N1 vs. N2 vs. N3), and MPTD (≤ 30 mm vs. > 30–50 mm vs. > 50 mm). For analysis of LRFS, the following additional covariates were taken into account: intracranial extension, skull base erosion, nasal extension, oropharyngeal extension, paranasopharyngeal extension and MPTD. We have only presented the results for MPTD and other statistically significant variables.