Table 2.
Multivariable analysis of PFS, LRF, and OS
| Covariate | PFS | LRF | OS | |||
|---|---|---|---|---|---|---|
| HR (95% CI) | P value | HR (95% CI) | P value | HR (95% CI) | P value | |
| All primary sites | (n = 514; 301 events) | (n = 514; 162 events) | (n = 514; 256 events) | |||
| Cetuximab (yes vs no) | 1.11 (0.89–1.40) | .3526 | 1.24 (0.91–1.70) | .1735 | 0.98 (0.77–1.26) | .8936 |
| Age (>50 vs ≤50 y) | 1.42 (1.05–1.90) | .0210 | 0.93 (0.65–1.33) | .6946 | 1.97 (1.39–2.79) | .0001 |
| Zubrod performance status (1 vs 0) | 1.20 (0.94–1.52) | .1418 | 1.31 (0.95–1.81) | .0988 | 1.43 (1.10–1.85) | .0068 |
| Pack-years of smoking (>10 vs ≤10) | 1.43 (1.08–1.91) | .0137 | 1.22 (0.83–1.78) | .3054 | 1.44 (1.06–1.97) | .0210 |
| p16-negative versus p16-positive OPC | 1.61 (1.11–2.32) | .0116 | 2.21 (1.37–3.57) | .0011 | 2.16 (1.45–3.22) | .0001 |
| Non-OPC versus p16-positive OPC | 1.87 (1.41–2.49) | <.0001 | 2.14 (1.44–3.19) | .0002 | 2.25 (1.65–3.09) | <.0001 |
| T category (T4 vs T2–3) | 1.16 (0.89–1.52) | .2721 | 1.42 (1.01–2.01) | .0468 | 1.13 (0.84–1.51) | .4207 |
| N category (N2c-3 vs N0-2b) | 1.38 (1.09–1.74) | .0079 | 1.65 (1.20–2.26) | .0019 | 1.29 (1.00–1.67) | .0497 |
| OPC | (n = 288; 135 events) | (n = 288; 74 events) | (n = 288; 108 events) | |||
| Cetuximab (yes vs no) | 1.19 (0.84–1.69) | .3160 | 1.59 (0.98–2.56) | .0592 | 0.98 (0.66–1.44) | .9135 |
| Age (>50 vs ≤50 y) | 1.49 (0.96–2.30) | .0743 | 1.00 (0.59–1.69) | .9885 | 2.38 (1.36–4.14) | .0022 |
| Zubrod performance status (1 vs 0) | 1.58 (1.10–2.29) | .0141 | 1.30 (0.79–2.14) | .2963 | 2.16 (1.45–3.23) | .0002 |
| Pack-years of smoking (>10 vs ≤10) | 1.48 (1.04–2.11) | .0314 | 1.11 (0.68–1.79) | .6803 | 1.31 (0.88–1.96) | .1820 |
| p16-negative versus p16-positive | 1.48 (1.02–2.16) | .0394 | 2.18 (1.34–3.57) | .0018 | 2.04 (1.36–3.07) | .0006 |
| T category (T4 vs T2–3) | 1.23 (0.84–1.80) | .2875 | 1.51 (0.92–2.47) | .1030 | 1.39 (0.92–2.10) | .1224 |
| N category (N2c-3 vs N0-2b) | 1.63 (1.15–2.32) | .0061 | 1.88 (1.17–3.01) | .0087 | 1.46 (0.99–2.17) | .0570 |
| p16-positive OPC | (n = 216; 91 events) | (n = 216; 44 events) | (n = 216; 68 events) | |||
| Cetuximab (yes vs no) | 1.26 (0.82–1.94) | .2912 | 2.04 (1.08–3.85) | .0283 | 0.93 (0.57–1.53) | .7772 |
| Age (>50 vs ≤50 years) | 1.50 (0.87–2.58) | .1424 | 0.88 (0.45–1.73) | .7188 | 3.42 (1.55–7.55) | .0024 |
| Zubrod performance status (1 vs 0) | 1.74 (1.10–2.76) | .0188 | 0.99 (0.49–2.00) | .9816 | 2.60 (1.55–4.35) | .0003 |
| Pack-years of smoking (>10 vs ≤10) | 1.51 (0.99–2.29) | .0546 | 1.01 (0.55–1.87) | .9624 | 1.23 (0.76–1.99) | .4079 |
| T category (T4 vs T2–3) | 1.05 (0.63–1.75) | .8408 | 1.41 (0.70–2.82) | .3327 | 1.19 (0.68–2.09) | .5446 |
| N category (N2c-3 vs N0-2b) | 1.34 (0.87–2.06) | .1806 | 1.69 (0.93–3.09) | .0869 | 1.01 (0.61–1.69) | .9681 |
| Non-OPC or p16-negative OPC | (n = 298; 210 events) | (n = 298; 118 events) | (n = 298; 188 events) | |||
| Cetuximab (yes vs no) | 1.02 (0.77–1.35) | .8776 | 1.04 (0.72–1.50) | .8419 | 0.96 (0.72–1.29) | .7945 |
| Age (>50 vs ≤50 y) | 1.38 (0.97–1.97) | .0752 | 0.93 (0.61–1.42) | .7279 | 1.66 (1.13–2.46) | .0103 |
| Zubrod performance status (1 vs 0) | 1.04 (0.79–1.38) | .7836 | 1.34 (0.93–1.94) | .1167 | 1.20 (0.89–1.60) | .2336 |
| Pack-years of smoking (>10 vs ≤10) | 1.43 (0.98–2.08) | .0641 | 1.36 (0.83–2.25) | .2232 | 1.60 (1.06–2.42) | .0247 |
| T category (T4 vs T2–3) | 1.17 (0.85–1.61) | .3276 | 1.47 (0.99–2.20) | .0590 | 1.09 (0.77–1.54) | .6422 |
| N category (N2c-3 vs N0-2b) | 1.41 (1.06–1.87) | .0177 | 1.63 (1.13–2.37) | .0098 | 1.40 (1.04–1.90) | .0267 |
Analysis was limited to patients with complete data for p16 status and pack-years.
Abbreviations: CI = confidence interval; HR = hazard ratio from multivariable Cox model; LRF = locoregional failure; OPC = oropharyngeal cancer; OS = overall survival; PFS = progression-free survival.