Table 1.

Study characteristics of studies included in meta-analysis. Oral Cavity (OC), Oropharynx (OP), Hypopharynx (HP), Larynx (L), Other (O), Surgery (S), Radiotherapy (RT), Chemotherapy (CT), Chemoradiotherapy (CRT), Formalin Fixed, Paraffin Embedded material (FFPE), Fresh Frozen Tissue (FFT), Tissuemicroarray (TMA), Immunohistochemistry (IHC), Immunofluorescence Staining (IFS).

Study	Sample size	Subsite	HPV	Stage	Treatment	Biomarkers	Material	Technique
Balermpas 2014	101	OC, OP, HP, L	Both	All	CRT	CD3, CD4, CD8, FoxP3	FFPE	IHC
Bron 2013	35	OC, OP, HP, L	?	All	S	FoxP3, (BDCA2, CD11c, CD56, COX2, BCL2, ARG2, iNOS)	FFPE	IHC
Distel 2009	115	OP, HP	?	All	CRT, S+RT	CD3, CD4, CD8, FoxP3, (CD20, CD79, Granzyme B)	FFPE in TMA	IHC
Hasmim 2013	83	OC, OP, HP, L	Both	All	S, CRT, S+RT	CD8, (HLA1, EPHRI-NE, SCINDERIN)	FFT	IHC, IFS
Kim 2016	402	OC, OP, HP, L, O	Both	All	S+CRT/RT/CT	CD3, CD8, FoxP3, (PD-L1, PD1, ICOS, LAG-1)	FFPE in TMA	IHC
Nasman 2012	83	OP	Both	All	RT, CRT	CD8, FoxP3	FFPE	IHC
Nguyen 2016	273	OC, OP, HP, L	?	All	S, RT, CRT	CD4, CD8, FoxP3, (CD68)	FFPE in TMA	IHC
Nordfors 2013	280	OP	Both	All	RT, CRT	CD4, CD8	FFPE	IHC
Oquejiofor 2015	139	OP	Both	All	RT	CD3, CD4, CD8, FoxP3, (SMA)	FFPE	IHC
Park 2013	79	OP	Both	III/IV	S, RT, S+RT	FoxP3, CD25	FFPE in TMA	IHC
Pretscher 2009	33	OC, OP, HP	Both	All	S+RT, S+CRT	CD3, CD8, FoxP3, (CD20, CD68, Granzyme B)	FFPE in TMA	IHC
Punt 2016	117	OP	Both	All	?	CD3, FoxP3, (IL-17)	FFPE	IFS
Van Kempen 2016	262	OP	Both	All	S, S+(C)RT, RT, CRT	CD3, CD4, CD8, (SERPENB1/B4/B9, Granzyme B)	FFPE in TMA	IHC
Watanabe 2010	87	OC	?	All	S	CD4, CD8, CD25, FoxP3, (CD69, CCR4, Granzyme B)	FFPE	IHC
Wolf 2015	39	OC	?	All	S, S+RT	CD4, CD8, FoxP3, (CD104, CD68)	FFPE in TMA	IHC
Zancope 2010	70	OC, O (lip)	?	All	S	CD8, (CD57)	FFPE	IHC