Univariate Cox Regression Analysis of Clinical Covariates for OS
| Covariate | Hazard ratio | 95% confidence interval | P |
| Treatment | <0.0001* | ||
| Surgery | 1 | ||
| Chemoradiotherapy | 0.5 | 0.3–0.9 | |
| Chemotherapy | 1.7 | 1.0–2.9 | |
| Expectative (none) | 3.3 | 1.7–6.3 | |
| Stage | 0.02* | ||
| I | 1 | ||
| II | 0.4 | 0.07–1.9 | |
| III | 1.6 | 0.6–4.4 | |
| IV | 4.3 | 1.4–13 | |
| Histologic subtype | |||
| Adenocarcinoma | 1 | 0.3 | |
| Squamous cell carcinoma | 0.7 | 0.4–1.4 | |
| Age | 1.01 | 1.0–1.1 | 0.4 |
↵* Statistically significant.