Table 1.

Quality assessment for each article

Reference	Risk of bias				Concerns regarding applicability
	Patient selection	Index test	Reference standard	Flow and timing	Patient selection	Index test	Reference standard
Gastro-oesophageal cancer
Abela et al.40	+	–	–	–	+	–	+
Amal et al.32	+	+	+	+	+	+	+
Amal et al.31	+	–	+	?	+	+	+
Chen et al.33	+	–	+	?	+	+	+
Daniel and Thangavel34	+	?	+	+	+	?	+
Duran-Acevedo et al.35	?	–	+	?	+	+	+
Kumar et al.42	–	–	+	+	+	+	+
Kumar et al.41	+	+	+	+	+	+	+
Markar et al.43	–	+	+	+	+	+	+
Schuermans et al.36	+	+	+	–	+	+	+
Shehada et al.37	?	+	?	?	+	+	?
Tong et al.38	?	?	?	?	+	–	?
Xu et al.39	–	+	+	?	+	+	+
Zou et al.44	?	–	?	?	+	+	?
Colorectal cancer
Altomare et al.49	+	+	+	?	+	+	+
Altomare et al.48	–	–	+	–	–	+	?
Amal et al.50	+	+	+	+	+	+	+
Peng et al.51	–	–	?	–	+	–	+
van de goor et al.52	+	+	+	?	–	+	+
Wang et al.53	–	–	+	+	+	+	+
Liver cancer
Qin et al.45	?	–	+	–	?	+	+
Pancreatic cancer
Markar et al.46	+	+	+	+	+	+	+
Princivalle et al.47	?	–	?	–	+	+	+

+, Low risk; –, high risk; ?, unclear risk.