Table 3.

Cause-specific survival.

	Definition #1 HR (95%CI)	p-value	Definition #2 HR (95%CI)	p-value
Model 1: not including pack-years or p16 status (n = 2688)
Gender (male vs. female)	1.17(1.02–1.36)	0.03	1.16(1.00–1.36)	0.05
Race (non-white vs. white)	1.29(1.13–1.46)	<0.001	1.30(1.14–1.49)	<0.001
Zubrod performance status (1–2 vs. 0)	1.65(1.47–1.85)	<0.001	1.59(1.41–1.80	<0.001
Primary site (non-oropharynx vs. oropharynx)	1.41(1.26–1.58)	<0.001	1.39(1.23–1.57)	<0.001
T stage (T4 vs. T1–3)	1.69(1.50–1.89)	<0.001	1.73(1.53–1.96)	<0.001
N stage (N2b-3 vs. N0–2a)	1.45(1.29–1.62)	<0.001	1.42(1.26–1.61)	<0.001
Age (≥ 70 vs. <70)	1.35(1.15–1.58)	<0.001	1.26(1.06–1.49)	0.009
Model 2: including pack-years and p16 status (n = 1043)
Gender (male vs. female)	1.06(0.84–1.35)	0.61	1.06(0.82–1.37)	0.64
Race (non-white vs. white)	1.01(0.80–1.27)	0.96	1.02(0.80–1.30)	0.86
Zubrod performance status (1–2 vs. 0)	1.52(1.25–1.84)	<0.001	1.47(1.20–1.81)	<0.001
Primary site (non-oropharynx vs. oropharynx)	1.05(0.85–1.29)	0.67	1.10(0.88–1.38)	0.39
T stage (T4 vs. T1–3)	1.73(1.42–2.11)	<0.001	1.81(1.47–2.23)	<0.001
N stage (N2b-3 vs. N0–2a)	1.51(1.24–1.83)	<0.001	1.50(1.22–1.85)	<0.001
Smoking history (>10 vs. ≤ 10 pack- years)	1.80(1.39–2.32)	<0.001	1.81(1.38–2.38)	<0.001
p16 status (negative vs. positive)	2.43(1.92–3.07)	<0.001	2.45(1.90–3.14)	<0.001
Age (≥ 70 vs. <70)	1.26(0.93–1.70)	0.14	1.19(0.87–1.64)	0.28
Model 3: including pack-years, p16 status, and interaction between p16 status and age (n = 1043)
Gender (male vs. female)	1.09(0.86–1.39)	0.47	1.08(0.84–1.39)	0.55
Race (non-white vs. white)	1.00(0.80–1.27)	0.97	1.02(0.80–1.30)	0.86
Zubrod performance status (1–2 vs. 0)	1.51(1.24–1.83)	<0.001	1.47(1.20–1.80)	<0.001
Primary site (non-oropharynx vs. oropharynx)	1.06(0.86–1.31)	0.58	1.11(0.89–1.39)	0.35
T stage (T4 vs. T1–3)	1.72(1.41–2.10)	<0.001	1.80(1.46–2.22)	<0.001
N stage (N2b-3 vs. N0–2a)	1.51(1.24–1.85)	<0.001	1.51(1.23–1.86)	<0.001
Smoking history (>10 vs. ≤ 10 pack- years)	1.78(1.37–2.29)	<0.001	1.79(1.36–2.35)	<0.001
p16 status (negative vs. positive) if age < 70	2.62(2.05–3.36)	<0.001	2.59(1.99–3.37)	<0.001
p16 status (negative vs. positive) if age ≥ 70	1.28(0.70–2.34)	0.42	1.47(0.75–2.87)	0.26
Age (≥ 70 vs. <70) if p16-positive	2.15(1.26–3.67)	0.005	1.86(1.01–3.42)	0.05
Age (≥ 70 vs. <70) if p16-negative	1.05(0.74–1.50)	0.78	1.05(0.73–1.52)	0.78
Interaction between p16 status and age	–	0.03	–	0.11

Cox models were stratified by trial (9003, 0129, 0522); HR, hazard ratio; CI, confidence interval.