Table 1. Characteristics of studies included in the meta-analysis.

First author	Year	Cases	Gender (M/F)	Median age	Inclusion period	Method	NOS score	Reference
Gong et al.	2017	73	NR	NR	2012-2017	IHC	7	[25]
Su et al.	2009	30	19/11	18.00	2004-2006	IHC	8	[16]
Zheng et al.	2009	30	19/12	24.50	2002-2006	SP	7	[26]
Han et al.	2009	35	23/12	20.38	2003-2007	SP	7	[17]
Lei et al.	2009	35	23/12	20.38	2003-2007	SP	8	[27]
Gu et al.	2008	64	38/26	21.40	1996-2001	SP	7	[28]
Xie et al.	2007	40	28/12	19.60	2001-2005	SP	8	[18]
Duan et al.	2007	40	28/12	19.60	2001-2005	SP	8	[29]
Chen et al.	2006	48	27/21	19.00	2000-2005	IHC	7	[30]
Zhong et al.	2006	40	22/18	23.00	1997-2003	SP	7	[31]
Liu et al.	2006	45	30/15	22.50	1990-2002	SP	8	[32]
Song et al.	2005	62	38/24	19.80	NR	SP	8	[33]
Huang et al.	2005	38	21/17	21.40	1995-2002	SP	7	[34]

Abbreviations: NR, no report; SP, streptavidin-perosidase.