Table 3.

Sensitivity analyses.

Variables	OS		HNCSS
	HR (95% CI)	P-value	HR (95% CI)	P-value
Primary site
Oropharynx
HPV-negative	Ref.		Ref.
HPV-positive	0.524 (0.392–0.701)	0	0.573 (0.416–0.789)	0.001
Hypopharynx
HPV-negative	Ref.		Ref.
HPV-positive	0.810 (0.304–2.159)	0.601	0.621 (0.180–2.141)	0.451
HPV-positive tumors
Radiotherapy
No	Ref.		Ref.
Yes	0.569 (0.371–0.872)	0.01	0.569 (0.358–0.905)	0.017
Surgery
No	Ref.		Ref.
Yes	0.745 (0.422–1.314)	0.309	0.549 (0.274–1.099)	0.091
HPV-negative tumors
Radiotherapy
No	Ref.		Ref.
Yes	0.712 (0.489–1.037)	0.077	0.736 (0.483–1.124)	0.156
Surgery
No	Ref.		Ref.
Yes	1.150 (0.631–2.096)	0.648	1.184 (0.613–2.289)	0.615

CI, confidence interval; HNCSS, head and neck cancers specific survival; HR, hazard ratio; HPV, human papillomavirus; Ref., reference; OS, overall survival.