Table 1.

The main characteristics of included 20 studies

Study	Year	Country	Type	Design	Sample	Num.	Stage	Cut-off	Follow-up	Test method	Outcome
Hu et al. [21]	2011	America	EC	R	Tissue	99	I-IV	Median	> 250	qRT-PCR	OS/DFS
Lin et al. [29]	2015	China	EC	R	Tissue	111	I-IV	Median	NR	qRT-PCR	OS
Osawa et al. [24]	2011	Japan	GC	R	Tissue	37	II-III	70%	60	qRT-PCR	OS
Hui et al. [22]	2015	China	GC	R	Tissue	76	I-III	Mean	> 60	qRT-PCR	OS
Wei et al. [30]	2015	China	GC	R	Tissue	157	I-IV	NR	> 100	qRT-PCR	OS
Zhang et al. [31]	2015	China	GC	R	Tissue	137	I-IV	2.44	68	qRT-PCR	OS
Yang et al. [23]	2015	China	GC	R	Tissue	50	I-IV	Median	60	qRT-PCR	OS
Li et al. [32]	2015	China	HCC	R	Tissue	114	I-IV	ROC	90	qRT-PCR	OS/PFS
Yang et al. [33]	2013	China	HCC	R	Tissue	30	NR	Mean	60	qRT-PCR	OS
Cui et al. [34]	2015	China	HCC	R	Tissue	120	NR	Median	60	qRT-PCR	OS/RFS
Xu et al. [20]	2015	China	HCC	R	Tissue	75	I-IV	Median	60	qRT-PCR	OS/RFS
Ohuchida et al. [35]	2011	Japan	PC	R	Tissue	90	NR	NR	>100	qRT-PCR	OS
Jamieson et al. [36]	2012	Scotland	PC	R	Tissue	72	NR	Median	48	qRT-PCR	OS
Long et al. [10]	2016	China	PC	R	plasma	159	I-IV	Mean	24	qRT-PCR	OS
Sun et al. [37]	2018	China	PC	R	Tissue	139	I-IV	Mean	60	qRT-PCR	OS
Zhang et al. [25]	2017	China	CRC	R	Tissue	84	I-IV	2	36	qRT-PCR	OS
Hasakova et al. [38]	2019	Slovakia	CRC	R	Tissue	64	I-IV	Median	100	qRT-PCR	OS
Gao et al. [39]	2014	China	CRC	R	Tissue	205	II-III	0.307	>80	qRT-PCR	DFS
Gao et al. [39]	2014	China	CRC	R	Tissue	63	II-III	0.307	>80	qRT-PCR	DFS
Jin et al. [11]	2013	China	GBC	R	Tissue	77	NR	Mean	24	qRT-PCR	OS

Abbreviations: CRC colorectal cancer; DFS disease-free survival, EC esophageal cancer; GBC gallbladder cancer; GC gastric cancer; HCC hepatocellular carcinoma, NR no report, OS overall survival, PC pancreatic cancer, PFS progressive-free survival, qRT-PCR quantitative real-time PCR, R retrospective, RFS recurrence-free survival