Effect of Metformin on the Prognosis of Gastric Cancer Patients with Type 2 Diabetes Mellitus: A Meta-Analysis Based on Retrospective Cohort Studies

Table 1

Characteristics of all the studies included in the meta-analysis.

Authors	Years	Countries	Sample size	Met users	Nonmet users	TNM stage					Adjusting factors
						I	II	III	IV	Unknown
Baglia	2019	American	130	81	49	NA					Sex, education, BMI, smoking, exercise, comorbidities, TNM stages, and cancer treatment
Chen	2020	China	71	51	20	16	4	3	48	0	Sex, age, hepatitis, tumor location, gastrectomy, reconstruction, lymphadenectomy, radical resection, and TNM stages
Chung	2020	China	651	248	403	239	137	275	0	0	Sex, age, Charlson comorbidity index, gastrectomy, lymphadenectomy, tumour size, differentiation, resection margins, TNM stages, vascular invasion, lymphatic invasion, perineural invasion, chemotherapy, and hypoglycemic medications
Lacroix	2018	Belgian	298	228	70	129	87	82	0	0	Age, sex, year of diagnosis, TNM stages, cancer treatment, and comorbidities
Lee	2016	Korea	326	132	194	178	60	88	0	0	Sex, age, BMI, use of insulin, cancer treatment, and TNM stages
Seo	2019	Korea	242	103	139	NA					Age, sex, ECOG, gastrectomy, and TNM stages
Zheng	2021	Sweden	1140	777	363	291		638		211	Sex, age, year of diagnosis, use of nonsteroidal anti-inflammatory drugs or aspirin, use of statins, and Charlson comorbidity index

Met, metformin; Nonmet, nonmetformin; NA, not available; TNM, tumor node metastasis classification; BMI, body mass index; ECOG, eastern cooperative oncology group.