Gastric neuroendocrine neoplasms type 1: A systematic review and meta-analysis

Table 1 Characteristics of the included studies

Included studies	Study design	No. of patients	Outcomes		Funding and conflict of interest statement
			Primary (positive LN status)	Secondary (R, DSS, complications)
Ahlman et al[13], 1994	Single-center restrospective cohort study	11	2/11 (data available at the individual level)	Median follow-up 5 yr; 100% 5-yr DSS	Funding: Swedish Mekong River Commission, Swedish Cancer Society, Jubileumsklinikens Cancer Research Fund, Sahlgrenska Hospital Research Foundation, Göteborg Medical Society, Assar Gabrielsson Research Foundation, Östergötland County Council and AB Hässle.
Borch et al[19], 2005	Multi-center prospective cohort study	51	4/51 (data not available at the individual level)	5-yr DSS reported for LN status and type of intervention strata. R also reported for different strata.	No funding or conflict of interest reported.
Chen et al[18], 2013	Single-center retrospective cohort study	56	2/56 (data not available at the individual level)	100% 5- and 10 yr DSS reported.	Funding: National Center for Advancing Translational Studies. The authors report no conflicts of interest.
Kim et al[25], 2010	Single-center retrospective cohort study	22	1/22 (data not available at the individual level)	Mean follow-up 68months for GC cohort; 5-yr DSS 100%. R: 15/22	No funding or conflict of interest reported
Louthan et al[24], 2014	Single-center retrospective cohort study	18	0/18 (data not available at the individual level)	Mean follow-up 47 months for GC cohort; 100% 5-yr DSS for type of intervention strata.	Funding: RVO VFN64165 and PRVOUK-P25/LF1/2.
Rappel et al[22], 1995	Single-center retrospective cohort study	88	0/88 (data not available at the individual level)	Median follow-up 72.2 mo; 100% 5-yr DSS; R: 26/54	No funding or conflict of interest information mentioned in the article.
Rindi et al[14], 1996	Multi-center retrospective cohort study	152	2/152 (data not available at the individual level)	Mean follow up 58months; 5-yr DSS 100%; R: 77/119	No funding or conflict of interest information mentioned in the article.
Safatle-Ribeiro et al[15], 2006	Single-center restrospective cohort study	13	1/13 (data available at the individual level)	Median follow-up 72.2 mo	No funding or conflict of interest information mentioned in the article.
Sagatun et al[17], 2016	Single-center restrospective cohort study	26	5/26 (data not available at the individual level)	Median follow-up not reported; 5-yr DSS not properly reported	No funding or conflict of interest reported.
Sato et al[20], 2014	Multi-center retrospective cohort study	82	0/82 (data not available at the individual level)	Median follow-up reported for different strata. 5-yr DSS not reported; R: 2/82.	No funding or conflict of interest reported.
Schindl et al[21], 2001	Single-center retrospective cohort study	16	0/16 (data not available at the individual level)	Median follow-up 70.3 mo; 5-yr DSS 100%.	No funding or conflict of interest information mentioned in article.
Thomas et al[23], 2013	Multi-center retrospective cohort study	111	2/111 (data not available at the individual level for all cases).	Mean follow up 76 mo; DSS not reported. R:8/111	Funding: Selander foundation. No conflict of interest reported.
Vanoli et al[16], 2018	Multi-center retrospective cohort study	123	6/123 (data not available at the individual level)	Median follow up 87 mo. 5-yr DSS reported for different strata.	Funding: Internal university grants and the Associazione Italiana Ricerca sul Cancro; Fellowship from San Matteo Hospital Foundation. Conflict of interest: Novartis Pharma and Ipsen Pharma.

DSS: Disease-specific survival; LN: Lymph node; R: Recurrence.

Table 2 Newcastle-Ottawa scale cohort star template

Included studies	Selection	Comparability	Outcome
Ahlman et al[13], 1994	***	*	**
Borch et al[19], 2005	****	**	**
Chen et al[18], 2015	***	*	**
Kiim et al[25], 2010	***	*	**
Louthan et al[24], 2014	***	*	**
Rappel et al[22], 1995	***	*	**
Rindi et al[14], 1996	***	**	**
Safatle-Ribeiro et al[15], 2006	***	**	**
Sagatun et al[17], 2016	***	*	*
Sato et al[20], 2014	***	*	*
Schindl et al[21], 2001	***	*	**
Thomas et al[23], 2013	***	*	**
Vanoli et al[16], 2018	***	**	**

The total Newcastle-Ottawa scale scores ranged from 0 (worst) to 9 (best) for the included cohort studies, with a score of at least 6 indicating high quality.