The Survival Effect of Metformin on Non-Small Cell Lung Cancer Treated with Chemotherapy: A Systematic Review

Table 2

Characteristics of the included studies.

Authors (publication year)	Study regions	Study year	Study design	Treatment strategies	Sample sizes (overall)	Sample sizes (metformin)	Quality assessment^d
Ahmed (2015)	United States	1999–2013	CCS^a	Paclitaxel + carboplatin + radiotherapy	166	20	8
Lin (2015)	United States	2007–2009	CCS	Chemotherapy NOS^b	349	227	7
Sayed (2015)	Egypt	2011–2013	RCT	Gemcitabine/Cisplatin regimen	30	15	High
Wink (2016)	Netherlands	2008–2013	CCS	Cisplatinum/carboplatin + etoposide + radiotherapy	682	59	8
Chuang (2018)	China	2000–2013	CCS	Cisplatin-base chemotherapy	2400	1193	8
Marrone (2018)	United States	2012–2015	RCT	Carboplatin, paclitaxel, and bevacizumab	24	18	High
Xin (2018)	China	2008–2011	CCS	Platinum-based chemotherapy NOS	75	27	8
Skinner (2021)	United States, Canada, and Israel	2014–2016	RCT	Carboplatin + paclitaxel + radiotherapy	167	86	High
Tsakiridis (2021)	Canada	2014–2019	RCT	(Cisplatin + etoposide)/(cisplatin + vinorelbine)/(carboplatin + etoposide/paclitaxel) + radiotherapy	54	26	High
Lee (2021)	Korea	2014–2018	RCT	Gemcitabine + carboplatin	164	81	High
Wang (2021)	Taiwan China	2004–2013	CCS	Pemetrexed-based platinum doublets NOS	495	225	8

^aCCS: case-control study; RCT: randomized controlled trials. ^bNOS: not otherwise specific. ^cNA: not available. ^dThe quality assessment tools were Cochrane collaboration’s tool for RCT and the Newcastle–Ottawa scale (NOS) for observational studies, respectively.