Table 2. Multivariable Cox Models for Progression-Free Survival (PFS) and Overall Survival (OS) in the Validation Cohort.

Variable	Primary Cox models		Cox models including cetuximab randomization
	Hazard ratio (95% CI)	P value	Hazard ratio (95% CI)	P value
PFS by molecular subtype
Molecular subtype
Canonical	1 [Reference]	NA	1 [Reference]	NA
Immune	0.4 (0.2-0.7)	.001	0.4 (0.2-0.7)	.001
Stromal	0.6 (0.4-0.9)	.01	0.6 (0.4-0.9)	.01
Clinical risk score
1	1 [Reference]	NA	1 [Reference]	NA
2	1.7 (0.9-3.3)	.09	1.8 (0.9-3.4)	.09
3	2.0 (1.0-3.7)	.04	2.0 (1.1-3.7)	.04
4	2.0 (0.9-4.6)	.10	2.0 (0.8-4.6)	.12
5	1.2 (0.2-9.4)	.86	1.1 (0.2-9.2)	.88
Cetuximab
No	NA	NA	1 [Reference]	NA
Yes	NA	NA	1.1 (0.7-1.6)	.72
OS by molecular subtype
Molecular subtype
Canonical	1 [Reference]	NA	1 [Reference]	NA
Immune	0.4 (0.2-0.9)	.02	0.4 (0.2-0.8)	.01
Stromal	0.7 (0.4-1.2)	.14	0.6 (0.3-1.0)	.06
Clinical risk score
1	1 [Reference]	NA	1 [Reference]	NA
2	1.7 (0.6-4.5)	.32	1.8 (0.7-5.0)	.23
3	2.7 (1.0-6.9)	.04	3.3 (1.2-8.5)	.02
4	2.7 (0.9-8.2)	.09	2.6 (0.8-7.9)	.10
5	2.2 (0.3-18.8)	.49	1.8 (0.2-15.5)	.61
Cetuximab
No	NA	NA	1 [Reference]	NA
Yes	NA	NA	2.0 (1.2-3.4)	.008
PFS by integrated risk
Integrated risk
Low	0.4 (0.2-0.8)	.006	0.4 (0.2-0.8)	.006
Intermediate	0.5 (0.3-0.9)	.02	0.5 (0.3-0.9)	.02
High	1 [Reference]	NA	1 [Reference]	NA
Cetuximab
No	NA	NA	1 [Reference]	NA
Yes	NA	NA	1.0 (0.7-1.5)	.94
OS by integrated risk
Integrated risk
Low	0.3 (0.1-0.8)	.02	0.3 (0.1-0.8)	.02
Intermediate	0.6 (0.3-1.2)	.16	0.6 (0.3-1.3)	.20
High	1 [Reference]	NA	1 [Reference]	NA
Cetuximab
No	NA	NA	1 [Reference]	NA
Yes	NA	NA	1.6 (1.0-2.5)	.06

Abbreviation: NA, not applicable.