Table 6.

Frequency of PIK3CA mutations identified in patients with esophageal squamous cell carcinoma worldwide

References	Year	Country (Region)	Patients of study	PIK3CA mutated (%)	Type of sample	Techniques
Mori et al. [24]	2008	Japan	88	2.2%	FT	Direct Sequencing
Wang et al. [30]	2013	China	76	3.9%	FT	Direct Sequencing
Akagi et al. [17]	2009	Japan	52	7.7%	FFPE	Direct Sequencing
Kim et al. [21]	2016	Korea	534	10.5%	FFPE	Direct Sequencing
Phillips et al. [25]	2006	Australia	35	11.8%	FFPE	Direct Sequencing
Zheng et al. [33]	2016	China	79	19.7%	FT	Pyrosequencing
Shigaki et al. [27]	2013	China	219	21.0%	FT	Pyrosequencing
Liu et al. [23]	2017	China	210	22.9%	FFPE	Pyrosequencing
Baba et al. [18]	2015	Japan	440	23.0%	FFPE	Pyrosequencing
Yang et al. [31]	2017	China	24	4.2%	FFPE	NGS
Song et al. [28]	2014	China	158	4.5%	FT	NGS
Lin et al. [22]	2014	China	139	7.0%	FFPE	NGS
Gao et al. [19]	2014	Japan	133	9.0%	FT	NGS
Sawada et al. [26]	2016	Japan	144	10.4%	FT	NGS
TCGA et al. [9]	2017	Western and Eastern	90	13.0%	FT	NGS
Yokota et al. [37]	2018	Japan	126	13.5%	FFPE	NGS
Zhang et al. [32]	2015	China	90	17.0%	FT	NGS
Wang et al. [29]	2015	USA	71	24.0%	FFPE	NGS

NGS – next generation sequencing; FFPE – formalin-fixed paraffin-embedded tissue; FT – fresh frozen tissue