OBJECTIVETo investigate the relationship between the environmental tobacco smoke (ETS) and lung cancer by Meta-analysis.

METHODSWe used "lung cancer/lung neoplasm", "non-smoking/non-smoker", "China/Chinese", "case-control/case control", "risk factor", "environmental tobacco smoke/passive smoking" as key words, to search papers in databases including Chinese BioMedical Literature (CBM), China National Knowledge Internet (CNKI), Wanfang, Vip Citation Databases (VIP), PubMed and Web of Science databases, and collected the case-control studies on ETS and lung cancer among Chinese non-smokers from January 1999 to December 2013. A total of 129 research papers were collected. RevMan 5.2 software was used to calculate combined odds radio (OR) and 95% CI.

RESULTSQualified 18 literatures were included, total cases 6 145 and controls 8 132. Consolidated results showed that ETS exposure could increase the risk of lung cancer, combined OR (95% CI) = 1.52 (1.42-1.64). Stratified analysis showed that ETS exposure was found to be significantly associated with an increasing risk of the lung cancer on non-smoking women and men, and combined OR (95% CI) were 1.58 (1.42-1.75) and 1.34 (1.08-1.65), respectively; the ETS exposure from family or the working environment could increase the risk of lung cancer, and combined OR (95% CI) were 1.48 (1.20-1.82) and 1.38 (1.13-1.69) respectively; childhood exposure and adult exposure were no significant statistical significance, and combined OR (95% CI) were 1.37 (0.98-1.91), and 1.34 (0.97-1.85) respectively.

CONCLUSIONEnvironmental tobacco smoke exposure was a significant risk factor of lung cancer among non-smokers in China.