Table 3.
Multivariate Cox Proportional Hazards Model of Local Failure
| Variable | HR | 95% CI | P* |
|---|---|---|---|
| RX duration, days | |||
| ≤ 53 | 1.00 | ||
| > 53 | 1.96 | 1.34 to 2.87 | .0006 |
| Treatment | |||
| RT + FU + mitomycin | 1.00 | ||
| RT + FU + cisplatin | 1.02 | 0.68 to 1.53 | .9220 |
| RT + FU | 2.44 | 1.69 to 3.51 | < .0001 |
| Age, continuous | 0.98 | 0.97 to 0.995 | .0067 |
| KPS | |||
| 90, 100 | 1.00 | ||
| 60, 70, 80 | 1.64 | 1.18 to 2.26 | .0030 |
| T stage | |||
| T1/T2 | 1.00 | ||
| T3/T4 | 1.961 | 1.459 to 2.635 | < .0001 |
| N stage | |||
| N0 | 1.00 | ||
| NX/N1/N2/N3 | 1.62 | 1.20 to 2.19 | .0018 |
| Total primary central axis dose (Gy), continuous | 0.98† | 0.96 to 0.995 | .0119 |
Abbreviations: HR, hazard ratio; RX, overall treatment; KPS, Karnofsky performance score.
*
P value from χ2 test using the Cox proportional hazards model.
†
Interpretation: An increase in dose of 1 Gy means a decrease in the hazard of local failure by 2%; an increase in dose of 5 Gy means a decrease in the hazard of local failure by 11%; an increase in dose of 10 Gy means a decrease in the hazard of local failure by 20%.