Table 2. Characteristics of included randomized controlled trials.

Study	Study design	Intervention	Stage of cancer	Metformin	Placebo	Median age (years)	Survival analysis	Adjusting variables	Duration and follow-up (year, months)	Jada scores
Reni et al, 2015, Italy.	Open-label, randomized, phase II trial	PEXG every 4 weeks in combination or not with 2 g oral metformin daily	Metastatic pancreatic cancer	31	29	Metformin:64 (42–75); Placebo:63 (44–73).	PFS at 6 months, PFS, OS	Age, CA 19-9, Karnofsky performance status, lymph nodes metastasis, peritoneum metastasis, SNP rs11212617, adiponectin, IL-6.	2010-2014, NR.	5
Kordes et al, 2015, Netherlands.	A double-blind, randomized, placebo-controlled phase 2 trial	Received either oral metformin or placebo twice daily.	Advanced pancreatic cancer	60	61	Metformin:64 (45–78);Placebo:65 (44–79).	OS at 6 months, OS, PFS	Tumor stage and diabetic state	2010-2014, 28.1m.	7

Abbreviations: NR: not reported; OS: overall survival; PFS: progression-free survival.