Table 4. Univariate and multivariate** association with overall survival.
| Covariate* | Multivariate OS | Univariate OS | |||||
|---|---|---|---|---|---|---|---|
| Hazard ratio (95% CI) | HR P value | Type 3 P value | Hazard ratio (95% CI) | HR P value | Log-rank P value | ||
| Histology | <0.001 | <0.001 | |||||
| Squamous cell carcinoma | 1.14 (1.06–1.24) | 0.001 | 1.23 (1.14–1.33) | <0.001 | |||
| Adenosquamous carcinoma | 1.52 (1.35–1.73) | <0.001 | 1.29 (1.15–1.46) | <0.001 | |||
| Adenocarcinoma | – | – | – | – | |||
| Chemotherapy | <0.001 | – | – | – | |||
| No | 1.71 (1.67–1.75) | <0.001 | |||||
| Unknown | 1.15 (1.08–1.23) | <0.001 | |||||
| Yes | – | – | |||||
| Surgery at primary site | <0.001 | – | – | – | |||
| No | 2.79 (2.73–2.86) | <0.001 | |||||
| Unknown | 2.42 (1.97–2.97) | <0.001 | |||||
| Yes | – | – | |||||
*, covariates in the multivariate model are: histology, race, sex, primary site, AJCC clinical T, N, M stage, surgery at primary site, chemotherapy, radiation, immunotherapy, and age at diagnosis; other covariates were not presented here to keep simplicity. **, backward selection with an alpha level of removal of 0.05 was used. No variables were removed from the model.