Table 1.

Study characteristics of (A) population-based studies and (B) observational cohort studies.

(A)
	Design				Outcomes
First Author Year	Enrolment Period	Country	Setting	Total Patients (n)	Incidence of GPM				Risk Factors for GPM
					Reported	n	%	Reported	Risk factors
Koemans [12] a 2021	2008–2017	The Netherlands	Nationwide register	12,504	Yes	2607	21%	No
Koemans [15] a 2020	1999–2017	The Netherlands	Nationwide register	34,943	No			Yes	−Non-cardia cancer −Age <45 years −Female sex −T2–T4 stage −>1 metastasis location −Diffuse type histology according to Lauren classification −Diagnosis in 2013–2017
Thomassen [16] 2013	1995–2012	The Netherlands	Regional register of southern part of the Netherlands	5220	Yes	706	14%	Yes	−Signet ring cell carcinoma −Linitis plastica −Non-cardia cancer −Age <60 years −Female sex −T3/T4 stage −N1–N3 stage −Poor tumour differentiation
Riihimäki [17] 2016	2002–2012	Sweden	Nationwide register	7559	Yes	936	12%	Yes	−Signet ring cell carcinoma −Non-cardia cancer −Age <60 years −Female sex
Choi [18] 2020	2004–2014	United States	State register of California	16,275	Yes	1691	10%	Yes	− Hispanic ethnicity
(B)
	Design				Outcomes
First Author Year	Enrolment Period	Country	Setting	Total Patients (n)	Incidence of GPM
					Reported		n		%
Seyfried [19] 2015	1986–2013	Germany	Single centre	1108	Yes		158		14%
Park [20] 2010	2000–2005	Korea	Single centre	3193	Yes		104		3%
Yu [21] 2010	1993–2006 1980–2003	JapanChina	Multicentre	2063 2496	Yes		42 324		2% 13%
Kim [22] 2003	1988–1998	Korea	Single centre	1833	Yes		267		15%
Yao [23] 2005	1985–1999	United States	Single centre	1897	Yes		200		11%
Isobe [24] 2013	1977–2006	Japan	Single centre	3818	Yes		447		12%

GPM indicates gastric peritoneal metastases. ^a Study contains same data register from The Netherlands.