Table 2.

Immunohistochemical technique used in the studies included in the meta-analysis.

Author	Year	Detection method	Primary antibody				Source	Cut-off value
			Antibody	Specie	Clone	Dilution
Ahn, S.	2019	IHC	Anti-PD-L1	Mouse, MAB	22C3	1 : 100	Dako, Carpinteria, CA, USA	1%
Arkenau, H. T.	2018	IHC	Anti-PD-L1	Mouse, MAB	22C3	NR	Agilent, Carpinteria, CA	1%
Dong, Z. T.	2020	IHC	Anti-PD-L1	MAB	NR	NR	Cell Signaling Technology, Inc. Danvers, MA, USA	5%
Gani, F.	2016	IHC	Anti-PD-L1	Mouse, MAB	5H1	NR	NR	5%
Gou, M. M.	2019	IHC	Anti-PD-L1	NR	NR	NR	NR	1%
Jing, C. Y.	2019	IHC	Anti-PD-L1	Rabbit, MAB	E1L3N	1 : 200	Cell Signaling Technology, MA, USA	5%
Kim, R.	2018	IHC	Anti-PD-L1	Mouse, MAB	5H1	NR	NR	1%
Kitano, Y.	2020	IHC	Anti-PD-L1	Rabbit, MAB	E1L3N	1 : 200	Cell Signaling Technology, Tokyo, Japan	5%
Kriegsmann, M.	2019	IHC	Anti-PD-L1	NR	SP263	NR	Roche AG, Rotkreuz, Switzerland	1%
Lim, Y. J.	2015	IHC	Anti-PD-L1	Rabbit, MAB	E1L3N	1 : 100	Cell Signaling Technology, Danvers, MA, USA	H-score 5
Lu, J. C.	2019	IHC	Anti-PD-L1	Rabbit, MAB	SP142	1 : 100	GeneTech Co. Ltd., Shanghai, China	5%
Ma, K.	2017	IHC	Anti-PD-L1	Rabbit, MAB	NR	1 : 250	Abcam, Cambridge, MA, USA	5%
Sangkhamanon, S.	2017	IHC	Anti-PD-L1	NR	NR	1 : 1000	Roche Diagnostic GmbH, USA	1%
Tamai, K.	2014	IHC	Anti-CD274	Rabbit, PAB	NR	NR	Abcam, Cambridge, MA, USA	++
Ueno, T.	2018	IHC	Anti-PD-L1	NR	NR	NR	NR	5%
Walter, D.	2017	IHC	Anti-PD-L1	Rabbit, MAB	E1L3N	1 : 50	Cell Signaling Technology, Danvers, MA, USA	Score 3
Yu, F.	2019	IHC	Anti-PD-L1	Rabbit, MAB	E1L3N	1 : 200	Cell Signaling Technology, Danvers, MA, USA	Score 3
Zhu, Y.	2018	IHC	Anti-PD-L1	Rabbit, MAB	SP142	1 : 50	Spring Bioscience, Inc., CA, USA	5%

MAB: monoclonal antibody; IHC: immunohistochemistry; NR: not reported; PAB: polyclonal antibody.