Table 2.
Multivariable Cox regression analysis of OS, DFS, LRR, and DM in patients across XRTOG 9501, RTOG 0234, and EORTC 22931
| OS |
DFS |
LRR |
DM |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Characteristic | HR | 95% CI | P value | HR | 95% CI | P value | sHR | 95% CI | P value | sHR | 95% CI | P value |
|
| ||||||||||||
| Age, y | 1 | 0.99, 1.01 | .903 | 1 | 0.99, 1.01 | .859 | 0.98 | 0.96, 0.99 | .005 | 0.99 | 0.97, 1.00 | .15 |
| Sex | ||||||||||||
| Male | - | - | - | - | - | - | - | - | ||||
| Female | 0.82 | 0.63, 1.08 | .163 | 0.89 | 0.69, 1.14 | .344 | 0.96 | 0.65, 1.43 | .857 | 0.84 | 0.57, 1.26 | .406 |
| Anatomic site | ||||||||||||
| Oral cavity | - | - | - | - | - | - | - | - | ||||
| Larynx | 0.63 | 0.49, 0.81 | <.001 | 0.71 | 0.56, 0.89 | .004 | 0.61 | 0.41, 0.89 | .011 | 1.16 | 0.79, 1.71 | .437 |
| Hypopharynx | 0.75 | 0.56, 0.99 | .04 | 0.8 | 0.61, 1.05 | .108 | 0.55 | 0.35, 0.86 | .009 | 1.88 | 1.26, 2.80 | .002 |
| Oropharynx | 0.5 | 0.40, 0.63 | <.001 | 0.56 | 0.46, 0.70 | <.001 | 0.66 | 0.47, 0.91 | .011 | 0.84 | 0.59, 1.20 | .344 |
| Tumor classification* | ||||||||||||
| T1 | - | - | ||||||||||
| T2 | 1.89 | 1.33, 2.69 | <.001 | 1.72 | 1.26, 2.36 | <.001 | 2.62 | 1.40, 4.91 | .003 | 1.73 | 0.99, 3.04 | .055 |
| T3 | 2.58 | 1.80, 3.68 | <.001 | 2.38 | 1.73, 3.28 | <.001 | 2.94 | 1.54, 5.61 | .001 | 2.08 | 1.18, 3.65 | .011 |
| T4 | 2.75 | 1.94, 3.91 | <.001 | 2.39 | 1.74, 3.26 | <.001 | 3.36 | 1.78, 6.33 | <.001 | 2.16 | 1.23, 3.77 | .007 |
| Number of nodes positive (spline)† | - | - | <.001 | - | - | <.001 | - | - | <.001 | - | - | <.001 |
| Number of nodes examined (spline) | - | - | .325 | - | - | .202 | - | - | .884 | - | - | .41 |
| Extranodal extension | ||||||||||||
| No | - | - | - | - | - | - | - | - | ||||
| Yes | 1.59 | 1.31, 1.93 | <.001 | 1.48 | 1.24, 1.77 | <.001 | 1.29 | 0.97, 1.73 | .085 | 1.59 | 1.20, 2.11 | .001 |
| Surgical margins | ||||||||||||
| Negative | - | - | - | - | - | - | - | - | ||||
| Positive | 1.23 | 0.99, 1.53 | .063 | 1.22 | 0.99, 1.50 | .059 | 1.38 | 1.02, 1.88 | .039 | 1.17 | 0.85, 1.63 | .332 |
| Adjuvant therapy | ||||||||||||
| Radiation therapy | - | - | - | - | ||||||||
| Chemoradiation | 0.8 | 0.66, 0.97 | .022 | 0.82 | 0.69, 0.99 | .034 | 0.62 | 0.46, 0.84 | .002 | 0.9 | 0.68, 1.19 | .459 |
| Trial | ||||||||||||
| EORTC 22931 | - | - | - | - | - | - | - | - | ||||
| RTOG 9501 | 1.17 | 0.94, 1.46 | .151 | 1.36 | 1.10, 1.68 | .004 | 0.94 | 0.67, 1.31 | .701 | 1.51 | 1.10, 2.07 | .01 |
| RTOG 0234 | 0.66 | 0.49, 0.88 | .005 | 0.9 | 0.68, 1.17 | .426 | 1.01 | 0.65, 1.56 | .981 | 1.21 | 0.79, 1.84 | .384 |
Abbreviations: AJCC = American Joint Committee on Cancer; CI = confidence interval; DFS = disease-free survival; DM= distant metastasis; HR = hazard ratio; LRR = locoregional recurrence; OS = overall survival; sHR = subdistributional HR.
*
AJCC seventh edition TNM (tumor, nodes, metastases) staging.
†
Left blank, as these variables were included in the multivariable model as a restricted cubic spline function due to nonlinear effect. Refer to Table 3 for results of piecewise linear regression for the HR for the spline segments.