BACKGROUND AND OBJECTIVEStudies of passive smoking exposure in China however are of particular interest, because of the high lung cancer rate in people who are mostly non-smokers. The aim of this study is to explore the relationship between passive smoking and lung cancer among non-smoking Chinese.

METHODSBy searching Medline, PubMed, CENTRAL (the Cochrane central register of controlled trials), CBM, CNKI and VIP, et al, we collected both domestic and overseas published documents between 1987 and 2007 on passive smoking and lung cancer among non-smoking Chinese. Random or fixed effect models were applied to conduct meta-analysis on the case control study results, and the combined odds ratio (OR) and the 95% confidence interval (CI) were calculated as well.

RESULTSSixteen documents were included into the combined analysis, which indicated that there was statistical significance between passive smoking and lung cancer (OR = 1.13, 95% CI: 1.05-1.21, P = 0.001). It was significant of lung cancer among non-smoking subjects associated with amount of tobacco passively smoked more than 20 cigarettes daily, with life period in adulthood passive smoking exposure, with gender female, and with exposure to workplace. The P value, OR and 95% CI were P = 0.0003, OR = 1.78, 95% CI: 1.30-2.43; P = 0.0001, OR = 1.50, 95% CI: 1.23-1.83; P = 0.000 7, OR = 1.50, 95% CI: 1.19-1.90; P < 0.0001, OR = 1.41, 95% CI: 1.19-1.66; respectively. And there was no significant difference between passive smoking and lung cancer with amount of tobacco passively smoked within 20 cigarettes daily, with life period in childhood passive smoking exposure, with gender male and with exposure to spouse and parents.

CONCLUSIONPassive smoking is an important risk factor of lung cancer among non-smoking Chinese, and for non-smoking women who expose to environment tobacco smoke in a long period of time have a close relationship with lung cancer risk.