Table 1.

Study characteristics.

Author	Ref. Nr.	Year	Country	Sample	Participants	Nr. CRC/CRA/HC
Zhang S. et al.	[37]	2020	China	S	253	161/34/58
Loftus M. et al.	[31]	2021	USA	F	252	74/N/178
Rezasoltani S. et al.	[32]	2022	Iran	S/F	40	Not Specified
Flemer B. et al.	[33]	2017	Ireland	S/CM/F	234	99/32/103
Wang Y. et al.	[42]	2021	China	S/CM/F	60	30/N/30
Yang Y. et al.	[43]	2019	USA	S	692	231/N/461
Idrissi J. et al.	[44]	2022	Canada	S/CM	43	22/N/21
Nosho K. et al.	[40]	2016	Japan	CM	511	511/0/0
Uchino Y. et al.	[34]	2021	Japan	S/F	103	52/N/51
Russo E. et al.	[35]	2018	Italy	S/CM/F	20	10/N/10
Pignatelli P. et al.	[41]	2021	Italy	S/CM	36	36/N/N
Tran H. et al.	[39]	2022	Vietnam	S/CM	63	42/21/N
Zhang X. et al.	[38]	2022	China	S	324	207/43/41/ HYP 33
Guven D. et al.	[36]	2019	Turkey	S	148	71/N/77

S—saliva samples; F—fecal samples; CM—colonic mucosa/tumor tissue; CRC—colorectal cancer; CRA—colorectal adenoma; HC—healthy control group; HYP—hyperplastic polyp.