1.

General characteristics of qualified studies included in the meta-analysis

First author	Year	Contry	Ethnicity	Number of cases (Male/Female)	Number of controls (Male/Female)	Histological types	Source of controls	Genotyping	Gene polymorphism	HWE
PCR-RFLP: polymerase chain reaction-restriction fragment length polymorphism; HWE: Hardy-Weinberg equilibrium.
Sun	2008	China	Asian	1, 163 (814/349)	1, 132 (781/351)	NA	Population based	PCR-RFLP	+49A > G, -1722A > G, -1661T > C, -318C > T, +6230G > A	0.909
Sun	2008	China	Asian	1, 032 (770/262)	1, 021 (771/250)	NA	Population based	PCR-RFLP	+49A > G, -1722A > G, -1661T > C, -318C > T, +6231G > A	0.152
Khaghanzadeh	2010	Iran	Caucasians	127 (105/22)	124 (89/35)	Squamous cell carcinoma, adenocarcinoma, small cell lung cancer, carcinoid tumors, non-well differentiated lung cancer	Population based	PCR-RFLP	+49A > G, -1722A > G, -1661T > C, -318C > T, +6232G > A, +1822C > T	> 0.050
Karabon	2011	Poland	Caucasians	208 (142/66)	326 (165/161)	Non-small cell lung cancer	Population based	PCR-RFLP	+49A > G, +319C > T, +6230G > A, +10223G > T	0.880
Antczak	2013	Poland	Caucasians	71 (46/25)	104 (NA/NA)	Non-small cell lung cancer (squamous cell carcinoma, adenocarcinoma, large cell carcinoma)	Population based	TaqMan	+49A > G, -318C > T	> 0.050
Liu	2015	China	Asian	231 (145/86)	250 (142/108)	Non-small cell lung cancer	Hospital based	PCR-RFLP	+49A > G	> 0.050
Ma	2015	China	Asian	528 (352/176)	600 (394/206)	Non-small cell lung cancer	Hospital based	PCR-RFLP	+49A > G, -318C > T	> 0.050
Chen	2017	China	Asian	549 (391/158)	611 (433/178)	Adenocarcinoma, squamous cell carcinoma, small cell lung cancer	Hospital based	TaqMan	+49A > G	> 0.050
Chen	2017	China	Asian	521 (287/234)	1, 030 (588/442)	Non-small cell lung cancer (adenocarcinoma, non-adenocarcinoma)	Hospital based	SNPscan Kit	+49A > G, -1722A > G, +6230G > A	> 0.050